Add "Community" section to docs, minor cleanup (#5993)

* Add 'Community' tab to navigation, move articles

* Drop DRF 2.x announcements and the docs note

* Drop embedded tutorial/guide/topics links

* Conver mixture of tabs/spaces => spaces

* Fix topics/community links

Author: Ryan P Kilby

docs/topics/3.0-announcement.md renamed to docs/community/3.0-announcement.md

@@ -119,7 +119,7 @@ This would now be split out into two separate methods.
         instance.save()
         return instance
 
-	def create(self, validated_data):
+    def create(self, validated_data):
         return Snippet.objects.create(**validated_data)
 
 Note that these methods should return the newly created object instance.
@@ -329,7 +329,7 @@ The `write_only_fields` option on `ModelSerializer` has been moved to `PendingDe
             model = MyModel
             fields = ('id', 'email', 'notes', 'is_admin')
             extra_kwargs = {
-            	    'is_admin': {'write_only': True}
+                    'is_admin': {'write_only': True}
             }
 
 Alternatively, specify the field explicitly on the serializer class:
@@ -454,15 +454,15 @@ We can now use this class to serialize single `HighScore` instances:
     def high_score(request, pk):
         instance = HighScore.objects.get(pk=pk)
         serializer = HighScoreSerializer(instance)
-	    return Response(serializer.data)
+        return Response(serializer.data)
 
 Or use it to serialize multiple instances:
 
     @api_view(['GET'])
     def all_high_scores(request):
         queryset = HighScore.objects.order_by('-score')
         serializer = HighScoreSerializer(queryset, many=True)
-	    return Response(serializer.data)
+        return Response(serializer.data)
 
 ##### Read-write `BaseSerializer` classes.
 
@@ -493,8 +493,8 @@ Here's a complete example of our previous `HighScoreSerializer`, that's been upd
                     'player_name': 'May not be more than 10 characters.'
                 })
 
-			# Return the validated values. This will be available as
-			# the `.validated_data` property.
+            # Return the validated values. This will be available as
+            # the `.validated_data` property.
             return {
                 'score': int(score),
                 'player_name': player_name

docs/topics/3.1-announcement.md renamed to docs/community/3.1-announcement.md

@@ -123,7 +123,7 @@ If you only wish to support a subset of the supported languages, use Django's st
         ('en', _('English')),
     ]
 
-For more details, see the [internationalization documentation](internationalization.md).
+For more details, see the [internationalization documentation][internationalization].
 
 Many thanks to [Craig Blaszczyk](https://github.com/jakul) for helping push this through.
 
@@ -205,5 +205,5 @@ This will either be made as a single 3.2 release, or split across two separate r
 [custom-exception-handler]: ../api-guide/exceptions.md#custom-exception-handling
 [pagination]: ../api-guide/pagination.md
 [versioning]: ../api-guide/versioning.md
-[internationalization]: internationalization.md
+[internationalization]: ../topics/internationalization.md
 [customizing-field-mappings]: ../api-guide/serializers.md#customizing-field-mappings

docs/topics/3.2-announcement.md renamed to docs/community/3.2-announcement.md

@@ -83,7 +83,7 @@ When using `allow_null` with `ListField` or a nested `many=True` serializer the
 
 For example, take the following field:
 
-    NestedSerializer(many=True, allow_null=True)
+    NestedSerializer(many=True, allow_null=True)
 
 Previously the validation behavior would be:
 
@@ -110,4 +110,4 @@ This release is planned to include:
 * Improvements and public API for our templated HTML forms and fields.
 * Nested object and list support in HTML forms.
 
-Thanks once again to all our sponsors and supporters.
+Thanks once again to all our sponsors and supporters.

docs/topics/3.3-announcement.md renamed to docs/community/3.3-announcement.md

@@ -37,8 +37,8 @@ This brings our supported versions into line with Django's [currently supported
 The AJAX based support for the browsable API means that there are a number of internal cleanups in the `request` class. For the vast majority of developers this should largely remain transparent:
 
 * To support form based `PUT` and `DELETE`, or to support form content types such as JSON, you should now use the [AJAX forms][ajax-form] javascript library. This replaces the previous 'method and content type overloading' that required significant internal complexity to the request class.
-* The `accept` query parameter is no longer supported by the default content negotiation class. If you require it then you'll need to [use a custom content negotiation class](browser-enhancements.md#url-based-accept-headers).
-*  The custom `HTTP_X_HTTP_METHOD_OVERRIDE` header is no longer supported by default. If you require it then you'll need to [use custom middleware](browser-enhancements.md#http-header-based-method-overriding).
+* The `accept` query parameter is no longer supported by the default content negotiation class. If you require it then you'll need to [use a custom content negotiation class][accept-headers].
+*  The custom `HTTP_X_HTTP_METHOD_OVERRIDE` header is no longer supported by default. If you require it then you'll need to [use custom middleware][method-override].
 
 The following pagination view attributes and settings have been moved into attributes on the pagination class since 3.1. Their usage was formerly deprecated, and has now been removed entirely, in line with the deprecation policy.
 
@@ -52,7 +52,9 @@ The following pagination view attributes and settings have been moved into attri
 
 The `ModelSerializer` and `HyperlinkedModelSerializer` classes should now include either a `fields` or `exclude` option, although the `fields = '__all__'` shortcut may be used. Failing to include either of these two options is currently pending deprecation, and will be removed entirely in the 3.5 release. This behavior brings `ModelSerializer` more closely in line with Django's `ModelForm` behavior.
 
-[forms-api]: html-and-forms.md
+[forms-api]: ../topics/html-and-forms.md
 [ajax-form]: https://github.com/encode/ajax-form
-[jsonfield]: ../../api-guide/fields#jsonfield
-[django-supported-versions]: https://www.djangoproject.com/download/#supported-versions
+[jsonfield]: ../api-guide/fields#jsonfield
+[accept-headers]: ../topics/browser-enhancements.md#url-based-accept-headers
+[method-override]: ../topics/browser-enhancements.md#http-header-based-method-overriding
+[django-supported-versions]: https://www.djangoproject.com/download/#supported-versions

docs/topics/3.4-announcement.md renamed to docs/community/3.4-announcement.md

@@ -185,10 +185,10 @@ The full set of itemized release notes [are available here][release-notes].
 [swagger]: https://openapis.org/specification
 [hyperschema]: http://json-schema.org/latest/json-schema-hypermedia.html
 [api-blueprint]: https://apiblueprint.org/
-[tut-7]: ../../tutorial/7-schemas-and-client-libraries/
-[schema-generation]: ../../api-guide/schemas/
-[api-clients]: api-clients.md
+[tut-7]: ../tutorial/7-schemas-and-client-libraries/
+[schema-generation]: ../api-guide/schemas/
+[api-clients]: ../topics/api-clients.md
 [milestone]: https://github.com/encode/django-rest-framework/milestone/35
 [release-notes]: release-notes#34
-[metadata]: ../../api-guide/metadata/#custom-metadata-classes
+[metadata]: ../api-guide/metadata/#custom-metadata-classes
 [gh3751]: https://github.com/encode/django-rest-framework/issues/3751

docs/topics/3.5-announcement.md renamed to docs/community/3.5-announcement.md

@@ -194,6 +194,6 @@ on realtime support, for the 3.7 release.
 
 [sponsors]: https://fund.django-rest-framework.org/topics/funding/#our-sponsors
 [funding]: funding.md
-[api-docs]: documenting-your-api.md
-[js-docs]: api-clients.md#javascript-client-library
-[py-docs]: api-clients.md#python-client-library
+[api-docs]: ../topics/documenting-your-api.md
+[js-docs]: ../topics/api-clients.md#javascript-client-library
+[py-docs]: ../topics/api-clients.md#python-client-library