Use #distinct instead of #uniq in the guides [ci skip]

* #uniq is an alias of #distinct
* #uniq will be deprecated, see: adfab2d

guides/source/active_record_querying.md

@@ -80,7 +80,7 @@ The methods are:
 * `reorder`
 * `reverse_order`
 * `select`
-* `uniq`
+* `distinct`
 * `where`
 
 All of the above methods return an instance of `ActiveRecord::Relation`.
@@ -999,7 +999,7 @@ SELECT categories.* FROM categories
   INNER JOIN articles ON articles.category_id = categories.id
 ```
 
-Or, in English: "return a Category object for all categories with articles". Note that you will see duplicate categories if more than one article has the same category. If you want unique categories, you can use `Category.joins(:articles).uniq`.
+Or, in English: "return a Category object for all categories with articles". Note that you will see duplicate categories if more than one article has the same category. If you want unique categories, you can use `Category.joins(:articles).distinct`.
 
 #### Joining Multiple Associations
 

guides/source/association_basics.md

@@ -2163,7 +2163,7 @@ You can use any of the standard [querying methods](active_record_querying.html)
 * `order`
 * `readonly`
 * `select`
-* `uniq`
+* `distinct`
 
 ##### `where`
 
@@ -2239,9 +2239,9 @@ If you use the `readonly` method, then the associated objects will be read-only
 
 The `select` method lets you override the SQL `SELECT` clause that is used to retrieve data about the associated objects. By default, Rails retrieves all columns.
 
-##### `uniq`
+##### `distinct`
 
-Use the `uniq` method to remove duplicates from the collection.
+Use the `distinct` method to remove duplicates from the collection.
 
 #### When are Objects Saved?