Updates the rust user group in coimbatore

The github repo will contain the details of the upcoming event and will be using the Mozilla Tamil Nadu social channels for advertising events.

Author: dvigneshwer

en-US/user-groups.md

@@ -64,6 +64,8 @@ even better, open a pull request against
 
 [Rust Group Bangalore](https://www.facebook.com/groups/RustBLR/1579069959026339/), Bangalore.
 
+[Rust Group Coimbatore](https://github.com/dvigneshwer/Rust_Group_Coimbatore), Coimbatore.
+
 ## Indonesia
 
 [Lambda Jakarta](https://www.meetup.com/Lambda-Jakarta/), Jakarta.