Correcting some spelling and grammar issues

lib/koans/15_processes.ex

@@ -157,7 +157,7 @@ defmodule Processes do
     assert_receive {:EXIT, _pid, ___}
   end
 
-  koan "If you monitor your children, you'll be automatically informed for their depature" do
+  koan "If you monitor your children, you'll be automatically informed of their departure" do
     spawn_monitor(fn -> Process.exit(self(), :normal) end)
 
     assert_receive {:DOWN, _ref, :process, _pid, ___}

lib/koans/18_protocols.ex

@@ -3,10 +3,10 @@ defmodule Protocols do
 
   @intro "Want to follow the rules? Adhere to the protocol!"
 
-  defprotocol School, do: def enrol(person)
+  defprotocol School, do: def enroll(person)
 
   defimpl School, for: Any do
-    def enrol(_) do
+    def enroll(_) do
       "Pupil enrolled at school"
     end
   end
@@ -21,31 +21,31 @@ defmodule Protocols do
   defmodule Baker, do: defstruct name: ""
 
   defimpl School, for: Musician do
-    def enrol(musician) do
+    def enroll(musician) do
       "#{musician.name} signed up for #{musician.instrument}"
     end
   end
 
   defimpl School, for: Dancer do
-    def enrol(dancer), do: "#{dancer.name} enrolled for #{dancer.dance_style}"
+    def enroll(dancer), do: "#{dancer.name} enrolled for #{dancer.dance_style}"
   end
 
   koan "Sharing an interface is the secret at school" do
     musician = %Musician{name: "Andre", instrument: "violin"}
     dancer = %Dancer{name: "Darcy", dance_style: "ballet"}
 
-    assert School.enrol(musician) == ___
+    assert School.enroll(musician) == ___
-    assert School.enrol(dancer) == ___
+    assert School.enroll(dancer) == ___
   end
 
   koan "Sometimes we all use the same" do
     student = %Student{name: "Emily"}
-    assert School.enrol(student) == ___
+    assert School.enroll(student) == ___
   end
 
   koan "If you don't comply you can't get in" do
     assert_raise ___, fn ->
-      School.enrol(%Baker{name: "Delia"})
+      School.enroll(%Baker{name: "Delia"})
     end
   end
 end