feat: add table describing supported feature gates and their default values

[lakshya8066]

What type of PR is this?
/kind documentation

What this PR does / why we need it:
Added a table of feature gates and their corresponding environment variables

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #4323

Special notes for your reviewer:

Checklist:

• squashed commits
• includes documentation
• adds unit tests
• adds or updates e2e tests

Release note:

Table of feature gates and their corresponding environment variables

[k8s-ci-robot]

Hi @lakshya8066. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[Skarlso]

/ok-to-test

[Skarlso]

This is nice, thank you for adding this. I'm not sure why we don't have anything like this.

[Skarlso]

Confirmed the values and names through feature/feature.go.

[Skarlso]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Skarlso

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