Use more idiomatic English for sentence (elixir-lang#758)

This commit changes "With this we are almost finishing our tour about Elixir modules. " to "With this we have almost finished our tour of Elixir modules."

Author: emwalker

getting-started/alias-require-and-import.markdown

@@ -166,7 +166,7 @@ defmodule Example do
 end
 ```
 
-With this we are almost finishing our tour about Elixir modules. The last topic to cover is module attributes.
+With this we have almost finished our tour of Elixir modules. The last topic to cover is module attributes.
 
 ## Understanding Aliases