copy: clarify in help text that `hg co --forget` takes a *destination* file We had a user who tried to pass a source file. The command then fails with `<file>: not unmarking as copy - file is not marked as copied`, so at least it's not just silent, but let's be a little clearer in the documentation. Differential Revision: https://phab.mercurial-scm.org/D9214