Add entry for GitHub Actions workflow_call notification service in RE…

…ADME

* Add a new entry for the GitHub Actions workflow_call notification service in the "Productivity Based Notifications" section
* Provide an example syntax for the new notification service

README.md

@@ -136,6 +136,7 @@ The table below identifies the services this tool supports and some example serv
 | [WxPusher](https://github.com/caronc/apprise/wiki/Notify_wxpusher) | wxpusher://  | (TCP) 443   | wxpusher://AppToken@UserID1/UserID2/UserIDN<br/>wxpusher://AppToken@Topic1/Topic2/Topic3<br/>wxpusher://AppToken@UserID1/Topic1/
 | [XBMC](https://github.com/caronc/apprise/wiki/Notify_xbmc) | xbmc:// or xbmcs://    | (TCP) 8080 or 443   | xbmc://hostname<br />xbmc://user@hostname<br />xbmc://user:password@hostname:port
 | [Zulip Chat](https://github.com/caronc/apprise/wiki/Notify_zulip) | zulip://  | (TCP) 443   | zulip://botname@Organization/Token<br />zulip://botname@Organization/Token/Stream<br />zulip://botname@Organization/Token/Email
+| [GitHub Workflow](https://github.com/caronc/apprise/wiki/Notify_github_workflow) | github+workflow:// | (TCP) 443 | github+workflow://token@repository/workflow
 
 ## SMS Notifications