debugupgraderepo: minor documentation fix When we specify `--no-changelog --no-manifest --no-filelog` we skip all revlog optimization instead of all filelog optimization. Also while I was here, for consistency, I did `optimisation` -> `optimization` to make it consistent with rest of occurrences. Note: I am not native speaker and I only changed it because of consistency. I don't know which one is correct. Differential Revision: https://phab.mercurial-scm.org/D9617