Remove Dotty Gitter channel and others (#1273)

Author: ennru

_data/chats-forums.yml

@@ -25,5 +25,3 @@ gitterChannels:
     url: https://gitter.im/scala-native/scala-native
   - name: scala-js/scala-js
     url: https://gitter.im/scala-js/scala-js
-  - name: lampepfl/dotty
-    url: https://gitter.im/lampepfl/dotty

community/index.md

@@ -69,7 +69,6 @@ Other, more specialized rooms include:
 * **[scala/job-board](https://gitter.im/scala/job-board)**: for employers and job seekers to connect with each other
 * **[scala-native/scala-native](https://gitter.im/scala-native/scala-native)**: for discussion about the Scala to LLVM compiler.
 * **[scala-js/scala-js](https://gitter.im/scala-js/scala-js)**: for discussion about the Scala to JavaScript compiler.
-* **[lampepfl/dotty](https://gitter.im/lampepfl/dotty)**: for discussion about the next generation Scala compiler.
 
 International rooms are available as well:
 
@@ -183,11 +182,6 @@ Staying current:
 * [Scala Native](https://www.scala-native.org) compiles Scala code to LLVM for native execution
 * [Scala on Android](https://scala-android.org) community site
 
-## Dotty
-
-* [Dotty](https://dotty.epfl.ch) is a next generation compiler for Scala, under development at EPFL
-    * [Dotty FAQ](https://dotty.epfl.ch/#why-dotty)
-
 ## The Scala Center
 
 * [The Scala Center](https://scala.epfl.ch/) is an open source foundation that brings together a coalition of individuals and organizations working together to contribute to Scala.