Add documentation for the Helm Operator OOM issue

[haywoodsh]

Proposed changes

Add documentation to advise users to watch single namespace or increase memory limit in case of an OOMkill event

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

[codecov-commenter]

Codecov Report

Merging #3470 (15ec556) into main (7c117ec) will increase coverage by 0.00%.
The diff coverage is n/a.

❗ Current head 15ec556 differs from pull request most recent head b21a07a. Consider uploading reports for the commit b21a07a to get more accurate results

@@           Coverage Diff           @@
##             main    #3470   +/-   ##
=======================================
  Coverage   51.97%   51.98%           
=======================================
  Files          60       60           
  Lines       16811    16806    -5     
=======================================
- Hits         8737     8736    -1     
+ Misses       7777     7775    -2     
+ Partials      297      295    -2     

Impacted Files	Coverage Δ
internal/configs/virtualserver.go	95.05% <0.00%> (-0.02%)	⬇️
pkg/apis/configuration/validation/virtualserver.go	94.38% <0.00%> (-0.01%)	⬇️
internal/configs/version2/http.go	0.00% <0.00%> (ø)
internal/k8s/configuration.go	95.79% <0.00%> (+0.36%)	⬆️

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