Add documentation for Serving probes

[ReToCode]

Proposed Changes

• Adds documentation for Add multi-container probing serving#14853

/assign @dprotaso
/assign @skonto

[knative-prow]

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[ReToCode]

@dprotaso gentle ping.

[skonto]

LGTM

A few suggestions. There is an opportunity to expand the whole section a bit with more info to educate users imho.

[ReToCode]

It is an opportunity to expand the whole section a bit with more info to educate users imho.

Good point, I'll see what I can add without making it too complex here (e.g. not all internas are really relevant to the "casual" user). But we maybe can also link the FT document that has a whole table of combinations as well?

[skonto]

But we maybe can also link the FT document that has a whole table of combinations as well?

Do we do this elsewhere? I am afraid we might change the implementation without changing the ft doc (happened before) because ft doc has its own lifecycle. So I would say let's keep one place where info is updated and copy what makes sense from the ft doc. wdyth?

[ReToCode]

I added more details in the docs. But I don't think this is the place to really put all the details about headers, how the components handle those and the exact rewriting. This documentation is focussing on the end-user and not Knative contributors. I think for those folks, the FTs + the actual code should be enough (at least it was for me working on this). An additional documentation is probably just going to be outdated at some point anyway.

[skonto]

Thanks @ReToCode for the updates some I added some minor comments. LGTM, I will wait @dprotaso for his review before merging or if he has no objection I can stamp it.

[ReToCode]

@skonto updated. I think we can go ahead without Dave here, as we can always update docs later on easily 👍 @dprotaso feel free to veto :)

[ReToCode]

/retest

[skonto]

/lgtm