NGF: Add document for upstream http2

[bjee19]

Proposed changes

Add document on supporting http2 to upstream through the appProtocol field on a Service.

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[bjee19]

This is a shorter guide which is technically covering a Kubernetes concept (Service's appProtocol), however I couldn't find a suitable document to include this information in. So I decided to write a standalone document for it.

[JTorreG]

hi @bjee19 can you please resolve the suggestions and re-request reviews in slack?

[sjberman]

@bjee19 This guide feels excessive for this use case. I feel like this could be as simple as saying what the protocol field does, and then end it there. Having a whole setup just to verify a single directive in the nginx config is too much in my opinion.

[bjee19]

@sjberman, I am definitely down to strip down this guide into what you suggested. However, would that entail just having it be a section in a larger document? I worry, that it would just get overshadowed if so. However, on the other end, having a separate document with such a small guide feels foreign.

[sjberman]

@bjee19 I'm not opposed this being its own, small guide.

[bjee19]

@salonichf5, do you have any thoughts or concerns about this guide just being a few small lines with no large setup? And it being its own separate guide?

[salonichf5]

@salonichf5, do you have any thoughts or concerns about this guide just being a few small lines with no large setup? And it being its own separate guide?

I am okay with it as well

[bjee19]

Updated by removing the example, let me know if you think the other sections aren't needed, however I see some value in them.