Add Mastodon Simplified Federation to misc projects

Watchlist-for-ActivityPub-developer-resources.md

@@ -12,6 +12,7 @@
   - [Testing](#testing)
 - [Miscellaneous projects](#miscellaneous-projects)
   - [Social sharing](#social-sharing)
+  - [Other projects](#other-projects)
 - [Reference material](#reference-material)
   - [Protocol specifications](#protocol-specifications)
   - [API documentation](#api-documentation)
@@ -152,6 +153,10 @@ This category is for any code project related to the Fediverse. They need not be
 
 * [**Share Freedom**](https://gitlab.com/mugcake/share-freedom-extension): Firefox toolbar extension to share the current browser tab to the Fediverse `GPL-3.0, Javascript`
 
+#### Other projects
+
+* [**Mastodon Simplified Federation**](https://github.com/rugk/mastodon-simplified-federation): Simplifies following and interacting with remote users on other Mastodon instances. `ISC, Javascript`
+
 ## Reference material
 
 #### Protocol specifications