Update pull_request_template.md

.github/pull_request_template.md

@@ -1,3 +1,18 @@
+
+<!--
+Please note that Rich isn't accepting any new features at this point.
+
+If a feature can be implemented without modifying the core library, then
+they should be released as a third-party module. I can accept updates to the
+core library that make it easier to extend (think hooks).
+
+Bugfixes are always welcome of course.
+
+Sometimes it is not clear what is a feature and what is a bug fix.
+If there is any doubt, please open a discussion first.
+
+-->
+
 ## Type of changes
 
 - [ ] Bug fix