doc: add documentation around Read-Only changesets
Created by: LawnGnome
Closes #26820 (closed), closes #36201 (closed).
This also adds a changelog entry for the whole project (under 3.42.0, since that's where it's shipping).
Test plan
Docs only.
Created by: LawnGnome
Closes #26820 (closed), closes #36201 (closed).
This also adds a changelog entry for the whole project (under 3.42.0, since that's where it's shipping).
Docs only.