Minor improvements to the PR template

[SaschaCowley]

Link to issue number:

Closes #17616

Summary of the issue:

There is inconsistent use of colons (":") after prompts in the PR template.

Description of user facing changes

• The PR template now has colons following all prompts
• The PR template now has a new "Developer facing changes" section
• The PR template now reminds users to use "Closes"/"Fixes"/"Resolves" to link the targetted issue
• The Pull Request Template Explanation and Examples document has been updated

Description of development approach

Read templates and made adjustments as necessary.
Read the template documentation, making minor fixes and documenting the new section.

Testing strategy:

Proof-read templates.

Known issues with pull request:

Users may dislike the change

Code Review Checklist:

• Documentation:
  • Change log entry
  • User Documentation
  • Developer / Technical Documentation
  • Context sensitive help for GUI changes
• Testing:
  • Unit tests
  • System (end to end) tests
  • Manual testing
• UX of all users considered:
  • Speech
  • Braille
  • Low Vision
  • Different web browsers
  • Localization in other languages / culture than English
• API is compatible with existing add-ons.
• Security precautions taken.

@coderabbitai summary

[seanbudd]

@SaschaCowley - can you resolve conflicts

[SaschaCowley]

@seanbudd done