Docs to include "feature"

[ShaneBeee]

Suggestion

I would like to suggest the addition of "feature" in the docs for syntaxes that are locked behind a feature.

1. an annotation like @Feature(Feature.SOME_FEATURE)
2. in the docs itself, above "since", have a "feature" area to show which feature needs to be enabled for this.

Why?

So people know which feature to use for something that is locked.
Exhibit A:
This section is locked behind using "for loop", but no mention of it anywhere in the docs

Other

No response

Agreement

• I have read the guidelines above and affirm I am following them with this suggestion.

[APickledWalrus]

Related: #7109 (not sure the docs implementation part will be covered in that PR)

[AyhamAl-Ali]

We can also have Experimental tag like the New tag