docs: explain how to untrack a file while keeping it in the working copy
Issue was fixed a while ago, but I forgot to update the
documentation.
@@ -15,8 +15,9 @@ will replace the previous working copy revision.
Also unlike most other VCSs, added files are implicitly tracked. That means that
if you add a new file to the working copy, it will be automatically committed
once you run e.g. `jj st`. Similarly, if you remove a file from the working
-copy, it will implicitly be untracked. There is no easy way to make it untrack
-already tracked files (https://github.com/martinvonz/jj/issues/14).
+copy, it will implicitly be untracked. To untrack a file while keeping it in
+the working copy, first make sure it's [ignored](#ignored-files) and then run
+`jj untrack <path>`.
Jujutsu currently supports only one working copy
(https://github.com/martinvonz/jj/issues/13).
