Add a How-To adjacent to Docs handbook on how to pull in tech reviews/contributions to missing feature gate docs

[drewhagen]

I've been a part of the SIG Release Team subproject for a few cycles. I've been in discussions on opportunities to clarify how to do things and process enhancements that could be better documented. Some of these come up as requested favors outside of the scope of subteam handbooks, favors that don't have clear guidance but could use some help to get done so I figure it might be useful for shadows and others to have some instruction sets of the things that come up. Not sure if feature request was the right template to use for this, so I'm open to feedback. 😄

What would you like to be added:

A how-to document (instruction set) for how release docs can help pull in technical reviewers and/or contributions for missed feature gates.

Why is this needed:

As @sftim pointed here out in our #release-docs slack channel (x-post), we've missed documentation on some 1.30 feature gates (also likely to have missed some for 1.31, though we're still discovering).

While we figure out how to catch these better in the future, an instruction set document would be useful to get more people clear on how we can trace feature gates in the kubernetes code, find contributors of feature gates, and pull them in with their SIG to ask that they either technically review docs produced by SIG Docs or retroactively contribute to the docs on their feature gate.

This instruction set could elaborate the simple steps I took on a comment like these:
kubernetes/website#47253 (comment)
kubernetes/website#47255 (comment)
With a clear instruction set, this work for 1.31 and beyond can more easily be divided as tasks amongst team members rather than tackled by one person.

How this would be added:

I'll add a PR soon that adds this instruction set under release-team/role-handbooks/docs/how-tos/

[sftim]

To be clear about the effort: @tengqm did all the detective work and I only shared it onward.