Add F# Section

Author: avestura

README.md

@@ -11,6 +11,7 @@ To get started, simply fork this repo. Please refer to [CONTRIBUTING.md](CONTRIB
 - [Clojure](#clojure)
 - [Elixir](#elixir)
 - [Erlang](#erlang)
+- [F#](#f)
 - [Go](#go)
 - [Haskell](#haskell)
 - [HTML/CSS](#html-and-css)
@@ -150,6 +151,10 @@ To get started, simply fork this repo. Please refer to [CONTRIBUTING.md](CONTRIB
 - [ChatBus : build your first multi-user chat room app with Erlang/OTP](https://medium.com/@kansi/chatbus-build-your-first-multi-user-chat-room-app-with-erlang-otp-b55f72064901)
 - [Making a Chat App with Erlang, Rebar, Cowboy and Bullet](http://marianoguerra.org/posts/making-a-chat-app-with-erlang-rebar-cowboy-and-bullet.html)
 
+## F#:
+
+- [Write your own Excel in 100 lines of F#](http://tomasp.net/blog/2018/write-your-own-excel)
+
 ## Java:
 
 - [Build an Interpreter](http://www.craftinginterpreters.com/) (Chapter 4-13 is written in Java)