docs: add helm chart readme

[akashsinghal]

Description

Adds a readme for helm chart values.
Inspiration from Gatekeeper's helm chart.

What this PR does / why we need it:

Which issue(s) this PR fixes (optional, using fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when the PR gets merged):

Fixes #564

Type of change

Please delete options that are not relevant.

• 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)
• Helm Chart Change (any edit/addition/update that is necessary for changes merged to the main branch)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Please also list any relevant details for your test configuration

• Test A
• Test B

Checklist:

• Does the affected code have corresponding tests?
• Are the changes documented, not just with inline documentation, but also with conceptual documentation such as an overview of a new feature, or task-based documentation like a tutorial? Consider if this change should be announced on your project blog.
• Does this introduce breaking changes that would require an announcement or bumping the major version?
• Do all new files have appropriate license header?

Post Merge Requirements

• MAINTAINERS: manually trigger the "Publish Package" workflow after merging any PR that indicates Helm Chart Change

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (af10ccc) 52.28% compared to head (f202287) 52.28%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1099   +/-   ##
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  Coverage   52.28%   52.28%           
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  Files         101      101           
  Lines        6291     6291           
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  Hits         3289     3289           
  Misses       2684     2684           
  Partials      318      318           

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[akashsinghal]

@binbin-li @susanshi appreciate a review on this whenever you have a chance. No rush on this.

[binbin-li]

Maybe it's quite a lot of work, wonder if we should pin to doc for each parameter or param group if we have doc on it.

[binbin-li]

lgtm. For the doc link, as we discussed in the community meeting, we can reconsider how to add it in the future.