Add doc updates

[oliviassss]

Issue

#3340
#3333
#3259
#3240

Description

Doc updates for:

• Update legacy provider section with in-tree controller
• Add a pathType note in Ingress Spec
• Update NLB security group section
• Add compatibility matrix of k8s version in helm chart README

Checked the rendering via make docs-preview.

Checklist

• Added tests that cover your change (if possible)
• Added/modified documentation as required (such as the README.md, or the docs directory)
• Manually tested
• Made sure the title of the PR is a good description that can go into the release notes

BONUS POINTS checklist: complete for good vibes and maybe prizes?! 🤯

• Backfilled missing tests for code in same general area 🎉
• Refactored something and made the world a better place 🌟

[codecov-commenter]

Codecov Report

Patch and project coverage have no change.

Comparison is base (aa893b5) 55.61% compared to head (bf183c8) 55.61%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3347   +/-   ##
=======================================
  Coverage   55.61%   55.61%           
=======================================
  Files         149      149           
  Lines        8819     8819           
=======================================
  Hits         4905     4905           
  Misses       3577     3577           
  Partials      337      337           

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[M00nF1sh]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: M00nF1sh, oliviassss

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