Docs for "experimental" features

[SchrodingersGat]

Body of the issue

Ref: #4982

• In the "getting started" space, we need a page discussing how we handle experimental features
• How to enable / disable features
• A list of currently available features
• Information on the "lifecycle" of such features

For each current experimental feature in the codebase, a page describing the feature in particular

[matmair]

I think a paragraph should be enough per feature - the docs are getting hard to navigate as they are.

[matmair]

@SchrodingersGat I do not think we will ship anything experimental for 0.12.0 - so do we need to include the docs with 0.12.0 or can we move this to 0.13.0?

[SchrodingersGat]

@matmair moved to 0.13.0 :)