apacheGH-2939: Update PULL_REQUEST_TEMPLATE (apache#2940)

* apacheGH-2939: Update PULL_REQUEST_TEMPLATE

* remove lengthy comments

Author: wgtmac

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,33 +1,30 @@
-Make sure you have checked _all_ steps below.
+<!--
+Thanks for opening a pull request!
 
-### Issue
+If you're new to Parquet-Java, information on how to contribute can be found here: https://parquet.apache.org/docs/contribution-guidelines/contributing
 
-- [ ] My PR addresses the following [GitHub issues](https://github.com/apache/parquet-java/issues) and references
-  them in the PR title. For example, "GH-1234: My Parquet PR"
-    - https://github.com/apache/parquet-java/issues/1234
-    - In case you are adding a dependency, check if the license complies with
-      the [ASF 3rd Party License Policy](https://www.apache.org/legal/resolved.html#category-x).
+Please open a GitHub issue for this pull request: https://github.com/apache/parquet-java/issues/new/choose
+and format pull request title as below:
 
-### Tests
+    GH-${GITHUB_ISSUE_ID}: ${SUMMARY}
 
-- [ ] My PR adds the following unit tests __OR__ does not need testing for this extremely good reason:
+or simply use the title below if it is a minor issue:
 
-### Commits
+    MINOR: ${SUMMARY}
 
-- [ ] My commits all reference GitHub issues in their subject lines. In addition, my commits follow the guidelines
-  from "[How to write a good git commit message](http://chris.beams.io/posts/git-commit/)":
-    1. Subject is separated from body by a blank line
-    1. Subject is limited to 50 characters (not including GitHub issue reference)
-    1. Subject does not end with a period
-    1. Subject uses the imperative mood ("add", not "adding")
-    1. Body wraps at 72 characters
-    1. Body explains "what" and "why", not "how"
+-->
 
-### Style
-- [ ] My contribution adheres to the code style guidelines and Spotless passes.
-    - To apply the necessary changes, run `mvn spotless:apply -Pvector-plugins`
+### Rationale for this change
 
-### Documentation
 
-- [ ] In case of new functionality, my PR adds documentation that describes how to use it.
-    - All the public functions and the classes in the PR contain Javadoc that explain what it does
+### What changes are included in this PR?
+
+
+### Are these changes tested?
+
+
+### Are there any user-facing changes?
+
+
+<!-- Please uncomment the line below and replace ${GITHUB_ISSUE_ID} with the actual Github issue id. -->
+<!-- Closes #${GITHUB_ISSUE_ID} -->