Added mostodon badge in readme, updated CLI

Author: ssddanbrown

bookstack-system-cli

@@ -9,6 +9,7 @@
 
 [![Repo Stats](https://img.shields.io/static/v1?label=GitHub+project&message=stats&color=f27e3f)](https://gh-stats.bookstackapp.com/)
 [![Discord](https://img.shields.io/static/v1?label=Discord&message=chat&color=738adb&logo=discord)](https://discord.gg/ztkBqR2)
+[![Mastodon](https://img.shields.io/static/v1?label=Mastodon&message=@bookstack&color=595aff&logo=mastodon)](https://fosstodon.org/@bookstack)
 [![Twitter](https://img.shields.io/static/v1?label=Twitter&message=@bookstack_app&color=1d9bf0&logo=twitter)](https://twitter.com/bookstack_app)
 [![YouTube](https://img.shields.io/static/v1?label=YouTube&message=bookstackapp&color=ff0000&logo=youtube)](https://www.youtube.com/bookstackapp)