Add fx to ECOSYSTEM.md (#3351)

Author: rikhuijzer

ECOSYSTEM.md

@@ -98,6 +98,7 @@ If your project isn't listed here and you would like it to be, please feel free
 - [sero](https://github.com/clowzed/sero): Host static sites with custom subdomains as surge.sh does. But with full control and cool new features. (axum, sea-orm, postgresql)
 - [Hatsu](https://github.com/importantimport/hatsu): 🩵 Self-hosted & Fully-automated ActivityPub Bridge for Static Sites.
 - [Mini RPS](https://github.com/marcodpt/minirps): Mini reverse proxy server, HTTPS, CORS, static file hosting and template engine (minijinja).
+- [fx](https://github.com/rikhuijzer/fx): A (micro)blogging server that you can self-host.
 
 [Realworld]: https://github.com/gothinkster/realworld
 [SQLx]: https://github.com/launchbadge/sqlx