docs(CHANGES): Note sync behavior with no args

Author: tony

CHANGES

@@ -24,6 +24,29 @@ $ pipx install --suffix=@next 'vcspull' --pip-args '\--pre' --force
 - Refreshed logo
 - `vcspull sync`:
 
+  - Empty command will now show help output
+
+    ```console
+    $ vcspull sync
+    Usage: vcspull sync [OPTIONS] [REPO_TERMS]...
+
+    Options:
+    -c, --config PATH Specify config
+    -x, --exit-on-error Exit immediately when encountering an error syncing
+    multiple repos
+    -h, --help Show this message and exit.
+    ```
+
+    To achieve the equivalent behavior of syncing all repos, pass `'*'`:
+
+    ```console
+    $ vcspull sync '*'
+    ```
+
+    Depending on how shell escaping works in your shell setup with [wild card / asterisk], you may not need to quote `*`.
+
+    [wild card / asterisk]: https://tldp.org/LDP/abs/html/special-chars.html#:~:text=wild%20card%20%5Basterisk%5D.
+
   - Terms with no match in config will show a notice (#394)
 
     > No repo found in config(s) for "non_existent_repo"