Add link to Supervisor cheat sheet (elixir-lang#855)

Author: benjamintanweihao

getting-started/mix-otp/supervisor-and-application.markdown

@@ -364,7 +364,9 @@ end
 
 Now, if the registry worker crashes, both the registry and the "rest" of `KV.Supervisor`'s children (i.e. `KV.Bucket.Supervisor`) will be restarted. However, if `KV.Bucket.Supervisor` crashes, `KV.Registry` will not be restarted, because it was started prior to `KV.Bucket.Supervisor`.
 
-There are other strategies and other options that could be given to `worker/2`, `supervisor/2` and `supervise/2` functions, so don't forget to check both [`Supervisor`](/docs/stable/elixir/Supervisor.html) and [`Supervisor.Spec`](/docs/stable/elixir/Supervisor.Spec.html) modules.
+There are other strategies and other options that could be given to `worker/2`, `supervisor/2` and `supervise/2` functions, so don't forget to check both [`Supervisor`](/docs/stable/elixir/Supervisor.html) and [`Supervisor.Spec`](/docs/stable/elixir/Supervisor.Spec.html) modules. 
+
+To help developers remember how to work with Supervisors and its convenience functions, [Benjamin Tan Wei Hao](http://benjamintan.io/) has created a [Supervisor cheat sheet](https://raw.githubusercontent.com/benjamintanweihao/elixir-cheatsheets/master/Supervisor_CheatSheet.pdf).
 
 There are two topics left before we move on to the next chapter.