Fix docs variable name
@@ -1821,7 +1821,7 @@ impl<'help> App<'help> {
///
/// let res = app.try_get_matches_from_mut(vec!["foo", "-x"]);
///
- /// // Since we changed `bar`'s short to "f" this should err as there
+ /// // Since we changed `foo`'s short to "f" this should err as there
/// // is no `-x` anymore, only `-f`
///
/// assert!(res.is_err());
