Improve listing of deprecated operations in namespace summary

[tcNickolas]

Is your feature request related to a problem? Please describe.
The current way deprecated operations are shown in the namespace summary is not informative: [!WARNING] it shows that something isn't right with this operation but doesn't provide more information.

Describe the solution you'd like
It would make sense to show deprecated operations as "[Deprecated]" followed by the summary of the operation, if it exists.

Additional context

[bettinaheim]

@cgranade Could you make sure this issue gets tracked/processed? I believe this would be applicable to docs gen.

[cgranade]

Sounds good, will look into supporting this enhancement as I have time to do so.