Add references

README.md

@@ -33,3 +33,9 @@ jobs:
       - name: upgrade mise tools
         uses: prefecthq/actions-mise-upgrade@main
 ```
+
+## References
+
+- https://github.com/jdx/mise/discussions/1823: this issue discusses workflows for plugin updates. Might be worth following along in case there ends up being a more 'official' way to do this.
+- https://github.com/jdx/mise/discussions/4057: this discussion mentions the `mise upgrade --bump` command we're using here, along with some context.
+- https://github.com/jdx/mise/discussions/4241: this discussion suggests adding a changelog to the `self-update` command, which is somewhat related and hopefully will carry over to the `upgrade` command for us to use in pull request descriptions.