DEV: Deprecate the plugin (#134)

Author: cvx

README.md

@@ -1,5 +1,8 @@
 # Discourse Github
 
+> [!IMPORTANT]
+> This plugin has now been bundled into Discourse core. See: https://meta.discourse.org/t/bundling-more-popular-plugins-with-discourse-core/373574
+
 https://meta.discourse.org/t/discourse-github/99895/
 
 This plugin combines functionality of deprecated github_badges and discourse-github-linkback plugins.