Docs: revert/cherry-pick squashed MRs with FF strategy
Problem to solve
I think !142152 (merged) covered part of the docs changes needed when discussing reverts / cherry-picks, but possibly not all of the changes. Also, I have Cherry-picking page: review / test all tasks (!141438 - merged) in flight, and I should recheck my work there in light of this change.
Related to Enable cherry-picking for fast-forward commits,... (#22236 - closed)