Fix capitalization

reading/recursion.livemd

@@ -153,8 +153,8 @@ You'll notice the **Process** memory consumption will increase, and eventually,
 You may need to click the **Connect** button to reconnect the Elixir runtime.
 
 ```elixir
-# defmodule Body Do
-#   def recursion([head | tail]) Do
+# defmodule Body do
+#   def recursion([head | tail]) do
 #     recursion(tail ++ tail) ++ [head]
 #   end
 # end