Formify issue templates and improve existing (#395)

* Update bug_report.md

* Rename bug_report.md to bug_report.yml

* Update and rename feature_request.md to feature_request.yml

* Create config.yml

* Update PULL_REQUEST_TEMPLATE.md

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,4 @@
+contact_links:
+  - name: 💬 Matrix Chat
+    url: https://matrix.to/#/#cinny:matrix.org
+    about: Ask questions and talk to other Cinny users and the maintainers