clean up various L10n strings (Igalia#711)

* Fixes Igalia#648 Clean up various L10n strings and add new ones

* Descriptions and key fixes

* Add an item that we are going to need for Bookmarks

* Updated the restart later description

Author: cvan

README.md

@@ -12,6 +12,11 @@ You can find us on Twitter [@MozillaReality](https://twitter.com/mozillareality)
 2. Click the `Firefox Reality for Android - Build - Master update →` link.
 3. Click the `Run Artifacts` tab, and click to download the APK for your platform of choice.
 
+## L10n
+
+Whenever a new string is added to a localizable strings file (strings.xml ,localpages.xml, ...) a string description must be provided as a comment above the new string. Also the project STRs wiki page must be updated with a key description, steps to reproduce and the expected results.
+The L10n wiki page can be found [here](https://github.com/MozillaReality/FirefoxReality/wiki/L10n).
+
 ## Setup instructions
 
 *Make sure you are using Android NDK r17b.*

app/src/main/res/values/localpages.xml

@@ -3,8 +3,14 @@
    - License, v. 2.0. If a copy of the MPL was not distributed with this
    - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
 <resources>
-    <!-- Private Browsing -->
+    <!-- IMPORTANT NOTE: If this file is updated anyhow, the STRs wiki must be updated accordingly:
+    https://github.com/MozillaReality/FirefoxReality/wiki/L10n -->
+
+    <!-- This string is used as the title of the Private Browsing page that is opened when the
+    Private Browsing Mode button from the tray is clicked. -->
     <string name="private_browsing_title">Private Browsing</string>
+    <!-- This string is used as the body of the Private Browsing page that is opened when the
+    Private Browsing Mode button from the tray is clicked. -->
     <string name="private_browsing_body"><![CDATA[
 <p>When you browse in a Private Window, %1$s <strong>does not save</strong>:</p>
 <ul class="two-column">