Add example of blueprint module import

Large-app-how-to.md

@@ -378,9 +378,14 @@ Here is the `/app/__init__.py`
         return render_template('404.html'), 404
 
     from app.users.views import mod as usersModule
-
     app.register_blueprint(usersModule)
 
+    # Later on you'll import the other blueprints the same way:
+    #from app.comments.views import mod as commentsModule
+    #from app.posts.views import mod as postsModule
+    #app.register_blueprint(commentsModule)
+    #app.register_blueprint(postsModule)
+
 now you can go in your root, activate your virtual env and run `python run.py` ... something like:
 
     brice@Brice:~/Projects/dev$ . env/bin/activate