cli: hyphenate "working-copy commit" in --ignore-working-copy help

The help text of `--ignore-working-copy` had one instance with hyphen
and one without.

cli/src/cli_util.rs

@@ -2947,7 +2947,7 @@ pub struct GlobalArgs {
     /// command. The working copy is also updated at the end of the command,
     /// if the command modified the working-copy commit (`@`). If you want
     /// to avoid snapshotting the working copy and instead see a possibly
-    /// stale working copy commit, you can use `--ignore-working-copy`.
+    /// stale working-copy commit, you can use `--ignore-working-copy`.
     /// This may be useful e.g. in a command prompt, especially if you have
     /// another process that commits the working copy.
     ///