Feature #2735 v6.0.0 beta6

[georgemccabe]

Besides adding the release notes and updating the version file, I added:

• A script to help generate release notes and entries to the release acceptance testing discussion
• Added/updated issue templates to include default titles and added Documentation issue template so issues can more easily be parsed by release notes script

Review release notes here:
https://metplus--2736.org.readthedocs.build/en/2736/Users_Guide/release-notes.html

[JohnHalleyGotway]

In principle, I approve of these changes, but did make a few suggestions on the PR for your consideration, along with this:

• Consider using Task for task template issues instead of Internal to avoid confusion.
• I note that none of the release notes are bolded. Please review and use your judgement to highlight any that should be emphasized.
• I reviewed the rendered release notes and like how you've set the script up to strip the prefix off of the issue title.
  • This is very subjective, but I always reword to the bugfix issues to state: "Fix {ABC} to do {XYZ}". Otherwise, we end up with a lot of variability in how info is communicated. Up to your discretion though.
• Reminder that issue templates only take effect when in the default branch. So you may want to make the same changes in main_v5.1 or consider switching to using develop as the default branch.
• Recommend updating the Release Guide instructions for writing release notes to point to the new utility script, along with debugging issues running it on seneca.