update README.md for 'bumver update --help'

README.md

@@ -586,6 +586,7 @@ Options:
   -p, --patch                   Increment patch component.
   -m, --minor                   Increment minor component.
   --major                       Increment major component.
+  -c, --commit-message <TMPL>   Set commit message template.
   --help                        Show this message and exit.
 ```
 

src/bumpver/cli.py

@@ -692,8 +692,8 @@ def _update_cfg_from_vcs(cfg: config.Config, fetch: bool) -> config.Config:
     "-c",
     "--commit-message",
     default=None,
-    metavar="<MESSAGE>",
-    help="Set commit message.",
+    metavar="<TMPL>",
+    help="Set commit message template.",
 )
 def update(
     dry           : bool = False,