Update PULL_REQUEST_TEMPLATE.md (#3395)

## Fixes #<!-- Link to relevant issue (for ex: #1234) which will automatically close the issue once the PR is merged. -->
Clear instructions on where to place the relevant issue number. 

<!-- Add a brief overview here of the feature/bug & fix. -->

## PR Type
What kind of change does this PR introduce?
<!-- Please uncomment one or more that apply to this PR. -->

<!-- - Bugfix -->
<!-- - Feature -->
<!-- - Code style update (formatting) -->
<!-- - Refactoring (no functional changes, no api changes) -->
<!-- - Build or CI related changes -->
- Documentation content changes 
<!-- - Sample app changes -->
<!-- - Other... Please describe: -->


## What is the current behavior?
<!-- Please describe the current behavior that you are modifying, or link to a relevant issue. -->
Lack of clear instructions causing confusion on where to place the issue number. 

## What is the new behavior?
<!-- Describe how was this issue resolved or changed? -->
Clear commented instructions on where to place the relevant issue numbers to assist bot in triggering "In-PR" label

## PR Checklist

Please check if your PR fulfills the following requirements:

- [ ] Tested code with current [supported SDKs](../readme.md#supported)
- [ ] Pull Request has been submitted to the documentation repository [instructions](..\contributing.md#docs). Link: <!-- docs PR link -->
- [ ] Sample in sample app has been added / updated (for bug fixes / features)
    - [ ] Icon has been created (if new sample) following the [Thumbnail Style Guide and templates](https://github.com/windows-toolkit/WindowsCommunityToolkit-design-assets)
- [ ] Tests for the changes have been added (for bug fixes / features) (if applicable)
- [ ] Header has been added to all new source files (run *build/UpdateHeaders.bat*)
- [X] Contains **NO** breaking changes

<!-- If this PR contains a breaking change, please describe the impact and migration path for existing applications below. 
     Please note that breaking changes are likely to be rejected. -->


## Other information

Author: msftbot[bot]

.github/ISSUE_TEMPLATE/bug_report.md

@@ -42,13 +42,15 @@ Windows 10 Build Number:
 - [ ] April 2018 Update (17134)
 - [ ] October 2018 Update (17763)
 - [ ] May 2019 Update (18362)
+- [ ] May 2020 Update (19041)
 - [ ] Insider Build (build number: )
 
 App min and target version:
 - [ ] Fall Creators Update (16299)
 - [ ] April 2018 Update (17134)
 - [ ] October 2018 Update (17763)
 - [ ] May 2019 Update (18362)
+- [ ] May 2020 Update (19041)
 - [ ] Insider Build (xxxxx)
 
 Device form factor:

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,4 +1,5 @@
-## Fixes #<!-- Link to relevant issue (for ex: #1234) which will automatically close the issue once the PR is merged. -->
+## Fixes #
+<!-- Add the relevant issue number after the "#" mentioned above (for ex: Fixes #1234) which will automatically close the issue once the PR is merged. -->
 
 <!-- Add a brief overview here of the feature/bug & fix. -->