Add GitHub discussions link; replace Google Group with netdev.chat

.github/ISSUE_TEMPLATE/config.yml

@@ -1,9 +1,12 @@
 # Reference: https://help.github.com/en/github/building-a-strong-community/configuring-issue-templates-for-your-repository#configuring-the-template-chooser
 blank_issues_enabled: false
 contact_links:
+  - name: ❓ Discussion
+    url: https://github.com/netbox-community/netbox/discussions
+    about: "If you're just looking for help, try starting a discussion instead"
   - name: 📖 Contributing Policy
     url: https://github.com/netbox-community/netbox/blob/develop/CONTRIBUTING.md
-    about: Please read through our contributing policy before opening an issue or pull request
-  - name: 💬 Discussion Group
-    url: https://groups.google.com/g/netbox-discuss
-    about: Join our discussion group for assistance with installation issues and other problems
+    about: "Please read through our contributing policy before opening an issue or pull request"
+  - name: 💬 Community Slack
+    url: https://netdev.chat/
+    about: "Join #netbox on the NetDev Community Slack for assistance with installation issues and other problems"