Document Annotations handled by DevWorkspace

[benoitf]

Description

Hello, looking at https://github.com/devfile/devworkspace-operator#annotations
I see that there is only one annotation being supported.

But when I discussed other items, in issue #630 (comment) there are other annotations

It would be nice to document them as it seems there are many there: https://github.com/devfile/devworkspace-operator/blob/5e82c76619c8ea10459d8310df6d7c015e08b416/pkg/constants/metadata.go

Additional context

[max-cx]

Hi, a question to the assignee of this issue:

Will the outcome require any changes to the relevant content of the Installation Guide or Administration Guide or End-user Guide?

Yes/No?