Improve some descriptions a little bit

lib/koans/04_tuples.ex

@@ -1,35 +1,35 @@
 defmodule Tuples do
   use Koans
 
-  koan "tuples have a size" do
+  koan "Tuples have a size" do
     assert tuple_size({:a, :b, :c}) == :__
   end
 
-  koan "tuples can contain different things" do
+  koan "Tuples can contain different things" do
     assert {:a, 1, "hi"} == :__
   end
 
-  koan "you can pull out individual elements" do
+  koan "You can pull out individual elements" do
     assert elem({:a, "hi"}, 1) == :__
   end
 
-  koan "you can change individual elements of a tuple" do
+  koan "You can change individual elements of a tuple" do
     assert put_elem({:a, "hi"}, 1, "bye") == :__
   end
 
-  koan "you can also simply extend a tuple with new stuff" do
+  koan "You can also simply extend a tuple with new stuff" do
     assert Tuple.insert_at({:a, "hi"}, 1, :new_thing) == :__
   end
 
-  koan "add things at the end" do
+  koan "Add things at the end" do
     assert Tuple.append({"Huey", "Dewey"}, "Louie") == :__
   end
 
-  koan "or also remove them" do
+  koan "Or remove them" do
     assert Tuple.delete_at({:this, :is, :not, :awesome}, 2) == :__
   end
 
-  koan "turn it into a list in case you need it" do
+  koan "Turn it into a list in case you need it" do
     assert Tuple.to_list({:this, :can, :be, :a, :list}) == :__
   end
 end