docs: Add elk.fedified.com to ecosystem list (#1837)

README.md

@@ -56,6 +56,7 @@ Note: The provided Dockerfile creates a container which will eventually run Elk
 
 These are known deployments using Elk as an alternative Web client for Mastodon servers or as a base for other projects in the fediverse:
 
+- [elk.fedified.com](https://elk.fedified.com) - Use Elk to log into any compatible instance
 - [elk.h4.io](https://elk.h4.io) - Use Elk for the `h4.io` Server
 - [elk.universeodon.com](https://elk.universeodon.com) - Use Elk for the Universeodon Server
 - [elk.vmst.io](https://elk.vmst.io) - Use Elk for the `vmst.io` Server