Update DG & PR template to improve release process

[tlylt]

What is the purpose of this pull request?

• Documentation update
• Bug fix
• Feature addition or enhancement
• Code maintenance
• DevOps
• Improve developer experience
• Others, please explain:

Overview of changes:

• adjust PR template to add a reviewer checklist
  • ensure version label is added
  • prepare release note
• adjust DG
  • reminders for the PR template changes
  • remind to double check version

Anything you'd like to highlight/discuss:
nil

Testing instructions:
https://deploy-preview-2361--markbind-master.netlify.app/devguide/projectmanagement

Proposed commit message: (wrap lines at 72 characters)
Update docs & PR template to improve release process

---

Checklist: ☑️

• Updated the documentation for feature additions and enhancements
• Added tests for bug fixes or features
• Linked all related issues
• No unrelated changes

[codecov]

Codecov Report

Merging #2361 (179eed1) into master (ebe9b9b) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #2361   +/-   ##
=======================================
  Coverage   45.11%   45.11%           
=======================================
  Files         123      123           
  Lines        5165     5165           
  Branches     1086     1086           
=======================================
  Hits         2330     2330           
  Misses       2516     2516           
  Partials      319      319           

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[ong6]

Lgtm