Fix a few formatting issues in the user guide. (#3145)

* Fix alignment in Data Types table.
* Fix Python line-wrapped indentation in Recommender Systems.

Author: brtal

userguide/recommender/choosing-a-model.md

@@ -117,7 +117,7 @@ for more information.
 
 ```python
 m = turicreate.ranking_factorization_recommender.create(data,
-			                              user_id='user',
+									user_id='user',
                                     item_id='movie',
                                     target='rating')
 ```
@@ -140,8 +140,8 @@ liked:
 
 ```python
 m = turicreate.item_similarity_recommender.create(data,
-                                                user_id='user',
-                                                item_id='movie')
+                                    user_id='user',
+                                    item_id='movie')
 ```
 
 The `ranking_factorization_recommender` is also great for implicit data,
@@ -150,7 +150,7 @@ and can be called the same way:
 
 ```python
 m = turicreate.ranking_factorization_recommender.create(data,
-			                              user_id='user',
+                                    user_id='user',
                                     item_id='movie')
 ```
 

userguide/sframe/sframe-intro.md

@@ -166,11 +166,11 @@ An SFrame is made up of columns of a contiguous type. For instance the `songs`
 SFrame is made up of 5 columns of the following types
 
 ```
-	song_id	str
-	title	str
-	release	str
+	song_id		str
+	title		str
+	release		str
 	artist_name	str
-	year	int
+	year		int
 ```
 
 In this SFrame we see only string (`str`) and integer (`int`) columns, but a