Add link to Platform Engineering slack

Signed-off-by: Joe Block <[email protected]>

Author: unixorn

README.md

@@ -498,6 +498,7 @@ There are GUI versions of `vim` and `emacs` that have ardent followers.
 
 - [DevOpsChat Slack](https://devopschat.co/) is another community of DevOps minded folk with a diverse set of topic specific chat rooms. Home to Arrested DevOps.
 - [Hangops Slack](https://signup.hangops.com/) is a community of DevOps minded folk with many subject focused chat rooms.
+- [Platform Engineering](https://platformengineering.org/) is a large community focused on platform engineering. Their [slack](https://platformengineering.org/slack-rd) has more than 15,000 users.
 - [PowerShell Slack](http://poshcode.org/) is a community of PowerShell enthusiasts and Windows centric DevOps topics.
 
 ## Windows Administration