Revert "refactor: move helm README to docs/helm.md"

[jsjoeio]

We think moving this broke the docs workflow

[codecov]

Codecov Report

Merging #4043 (f319fca) into main (c913386) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #4043   +/-   ##
=======================================
  Coverage   63.51%   63.51%           
=======================================
  Files          36       36           
  Lines        1872     1872           
  Branches      379      379           
=======================================
  Hits         1189     1189           
  Misses        580      580           
  Partials      103      103           

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[github-actions]

✨ Coder.com for PR #4043 deployed! It will be updated on every commit.

• Host: https://codercom-qoz8gm5c7-codercom.vercel.app/docs/code-server
• Last deploy status: success
• Commit: f319fca
• Workflow status: https://github.com/cdr/code-server/actions/runs/1167761154

[jsjoeio]

Note: we did not fully wait for CI to complete because this is a simple revert. We noticed this fixed the docs issue so we merged.