tls:remove unimplemented options from one of description

[ramaraochavali]

Commit Message: remove unimplemented options from one of description
Additional Description:
Risk Level: N/A
Testing: N/A
Docs Changes: N/A
Release Notes: N/A

[repokitteh-read-only]

CC @envoyproxy/api-shepherds: Your approval is needed for changes made to (api/envoy/|docs/root/api-docs/).
envoyproxy/api-shepherds assignee is @lizan
CC @envoyproxy/api-watchers: FYI only for changes made to (api/envoy/|docs/root/api-docs/).

🐱

Caused by: #27786 was opened by ramaraochavali.

see: more, trace.

[ravenblackx]

Review SLA ping @lizan

[adisuissa]

I think this was added in #17201, and these options may be in-use by gRPC.
If so, a note can be added describing which fields are relevant for Envoy.

@markdroth can you PTAL?

[KBaichoo]

Can you chime in @markdroth ? Thanks

[markdroth]

That's correct, gRPC does implement the tls_certificate_provider_instance field, and it is mutually exclusive with the other two, so the comment is correct as-is. If you want to add a note that Envoy does not yet support that field, that's fine.

[ramaraochavali]

If there is a plan for Envoy to support that in future, I think we can close this.