Docs: Relocate alpha_k8s_apis to configuration sections across docs

[svteb]

Description

Should move all k8s API related stuff to the correct configuration sections across doc files.

Interestingly there were as of yet unimplemented TO DO'S in USAGE.md and TEST_CATEGORIES.md which were also moved for future coherence (these relate to the k8s APIs category).

Issues:

Refs: #2077

How has this been tested:

• [ ] Covered by existing integration testing
• [ ] Added integration testing to cover
• [ ] Verified all A/C passes
  • [ ] develop
  • [ ] master
  • [ ] tag/other branch
• [ ] Test environment
  • [ ] Shared Packet K8s cluster
  • [ ] New Packet K8s cluster
  • [ ] Kind cluster
• [ ] Have not tested

Types of changes:

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [x] Documentation update

Checklist:

Documentation

• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] No updates required.

Code Review

• [ ] Does the test handle fatal exceptions, ie. rescue block

Issue

• [x] Tasks in issue are checked off

[svteb]

I am not sure if I covered all the doc files, if I missed something write a comment.

[martin-mat]

@svteb please rebase and adapt to the new doc structure

[svteb]

I will rebase after #2089 is merged to avoid some issues.