Add FS2 to Related Projects section

Also alphabetize Related Projects list

README.md

@@ -123,9 +123,10 @@ relax this to a single sign-off.
 There are many projects that integrate with Cats:
 
  * [Dogs](https://github.com/stew/dogs): pure functional collections and data structures.
- * [Kittens](https://github.com/milessabin/kittens): automatically derived type class instances.
  * [Circe](https://github.com/travisbrown/circe): pure functional JSON library.
- * [Fetch](https://github.com/47deg/fetch): efficient data access to heterogeneous data sources. 
+ * [Fetch](https://github.com/47deg/fetch): efficient data access to heterogeneous data sources.
+ * [FS2](https://github.com/functional-streams-for-scala): compositional, streaming I/O library
+ * [Kittens](https://github.com/milessabin/kittens): automatically derived type class instances.
  * [Monix](https://github.com/monixio/monix): high-performance library for composing asynchronous and event-based programs.
 
 ### Copyright and License