Add issue template

Author: Andrew Godwin

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,14 @@
+Issues are for **concrete, actionable bugs and feature requests** only - if you're just asking for debugging help or technical support we have to direct you elsewhere. If you just have questions or support requests please use:
+
+- Stack Overflow
+- The Django Users mailing list [email protected] (https://groups.google.com/forum/#!forum/django-users)
+
+We have to limit this because of limited volunteer time to respond to issues!
+
+Please also try and include, if you can:
+
+- Your OS and runtime environment, and browser if applicable
+- A `pip freeze` output showing your package versions
+- What you expected to happen vs. what actually happened
+- How you're running Channels (runserver? daphne/runworker? Nginx/Apache in front?)
+- Console logs and full tracebacks of any errors