Add issue templates for the new issue template chooser

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,11 @@
+blank_issues_enabled: false
+contact_links:
+  - name: OpenRA Forum
+    url: https://forum.openra.net/
+    about: "Please ask questions about modding here."
+  - name: OpenRA Discord server
+    url: https://discord.openra.net/
+    about: "Join the community Discord server for community discussion and support."
+  - name: OpenRA IRC Channel
+    url: https://webchat.freenode.net/#openra
+    about: "Join our development IRC channel on freenode for discussion of development topics."