Update readme with Commit field changes

Signed-off-by: Riddhesh Sanghvi <riddhesh237@gmail.com>

README.md

@@ -52,7 +52,7 @@ SLACK_COLOR       | `good` (green)                                        | You
 SLACK_MESSAGE     | Generated from git commit message.                    | The main Slack message in attachment. It is advised not to override this.
 SLACK_TITLE       | Message                                               | Title to use before main Slack message.
 SLACK_FOOTER      | Powered By rtCamp's GitHub Actions Library            | Slack message footer.
-MSG_MINIMAL       | -                                                     | If set to `true`, removes: `Ref`, `Event` and `Actions URL` from the message. You can optionally whitelist any of these 3 removed values by passing it comma separated to the variable instead of `true`. (ex: `MSG_MINIMAL: event` or `MSG_MINIMAL: ref,actions url`, etc.)
+MSG_MINIMAL       | -                                                     | If set to `true`, removes: `Ref`, `Event`,  `Actions URL` and `Commit` from the message. You can optionally whitelist any of these 4 removed values by passing it comma separated to the variable instead of `true`. (ex: `MSG_MINIMAL: event` or `MSG_MINIMAL: ref,actions url`, etc.)
 
 You can see the action block with all variables as below: