Add phoenix app skeleton
Add LICENSE file
Remove phoenix
Add watcher module
Responsible for limiting the number of processes spawned
from a certain process. It uses 2 ets tables.

The first table contains the process counter for all the
processes being watched. Table object: {pid, counter}.

The second table contains the references for the process monitors
relative to a process being watched. Table object: {reference, pid}.

A process must be spawned with Tryelixir.Watcher.spawm/2, which returns
{:ok, pid} on success, {:error, reason} otherwise.

Example:

pid = self()

Tryelixir.Watcher.start_link()
Tryelixir.Watcher.add(pid)
{:ok, pid} = Tryelixir.Watcher.spawn(pid, fn -> :ok end)
Add initial work on the REPL
Add tutorial intro
Move english tutorial to a separate folder
Add t1
Remove old intro.md
Add t2
Add t3
Add t4
Add t5
Add t6
Add t7
Add t8
Add t9
Add t10
Add t11
Add outro