Update issue templates (#25912)

* Update issue templates

To perhaps make it clearer that https://discuss.akka.io is the place for questions?

* Remove top-level template in favour of multiple templates

* Remove unintentional hyphens, reword feature request template

.github/ISSUE_TEMPLATE/---bug-report.md

@@ -1,6 +1,10 @@
-<!-- 
-We use the issue tracker for bugs and feature requests. For general questions and discussion please use https://discuss.akka.io or https://gitter.im/akka/akka instead.
+---
+name: "\U0001F41B Bug report"
+about: Create a report to help us improve
 
+---
+
+<!--
 Please report issues regarding specific projects in their respective issue trackers, e.g.:
  - Akka HTTP: https://github.com/akka/akka-http/issues
  - Alpakka:   https://github.com/akka/alpakka/issues

.github/ISSUE_TEMPLATE/---feature-request.md

@@ -0,0 +1,17 @@
+---
+name: "\U0001F389 Feature request"
+about: Suggest an idea for this project
+
+---
+
+<!--
+Please report issues regarding specific projects in their respective issue trackers, e.g.:
+ - Akka HTTP: https://github.com/akka/akka-http/issues
+ - Alpakka:   https://github.com/akka/alpakka/issues
+ - Akka Persistence Cassandra Plugin: https://github.com/akka/akka-persistence-cassandra/issues
+ - ...
+
+Please explain your use case precisely, and if possible provide an example snippet.
+
+Thanks, happy hakking!
+-->

.github/ISSUE_TEMPLATE/--question.md

@@ -0,0 +1,7 @@
+---
+name: "❓ Question"
+about: Please use https://discuss.akka.io for questions
+
+---
+
+Please use https://discuss.akka.io for questions instead of posting them to the issue tracker.