Docs - we should recommend mirroring namespaces in project-base when extending framework classes

[vitek-rostislav]

We are recommending this indirectly in our cookbooks, the prepared extensions in project-base do that as well, however, it is never mentioned directly anywhere. Part of the annotations fixer functionality relies on the fact (see #1344 (comment))

What is happening

Expected result

Our docs explicitly recommend mirroring namespaces when developers extend classes from the framework in their project.

[stale]

This issue has been automatically marked as stale because there was no activity within the last 4 months (and it is quite a long time). It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue has been automatically closed because there was no acivity within the last half a year.