Fix typos.

docs/api-guide/relations.md

@@ -43,7 +43,7 @@ In order to explain the various types of relational fields, we'll use a couple o
 
 For example, the following serializer.
  
-    class AlbumSerializer(serializer.ModelSerializer):
+    class AlbumSerializer(serializers.ModelSerializer):
         tracks = RelatedField(many=True)
         
         class Meta:
@@ -75,7 +75,7 @@ This field is read only.
 
 For example, the following serializer:
  
-    class AlbumSerializer(serializer.ModelSerializer):
+    class AlbumSerializer(serializers.ModelSerializer):
         tracks = PrimaryKeyRelatedField(many=True, read_only=True)
         
         class Meta:
@@ -109,7 +109,7 @@ By default this field is read-write, although you can change this behavior using
 
 For example, the following serializer:
  
-    class AlbumSerializer(serializer.ModelSerializer):
+    class AlbumSerializer(serializers.ModelSerializer):
         tracks = HyperlinkedRelatedField(many=True, read_only=True,
                                          view_name='track-detail')
         
@@ -149,7 +149,7 @@ By default this field is read-write, although you can change this behavior using
 
 For example, the following serializer:
  
-    class AlbumSerializer(serializer.ModelSerializer):
+    class AlbumSerializer(serializers.ModelSerializer):
         tracks = SlugRelatedField(many=True, read_only=True, slug_field='title')
         
         class Meta:
@@ -223,12 +223,12 @@ Note that nested relationships are currently read-only.  For read-write relation
 
 For example, the following serializer:
 
-    class TrackSerializer(serializer.ModelSerializer):
+    class TrackSerializer(serializers.ModelSerializer):
         class Meta:
             model = Track
             fields = ('order', 'title')
     
-    class AlbumSerializer(serializer.ModelSerializer):
+    class AlbumSerializer(serializers.ModelSerializer):
         tracks = TrackSerializer(many=True)
         
         class Meta:
@@ -265,7 +265,7 @@ For, example, we could define a relational field, to serialize a track to a cust
             duration = time.strftime('%M:%S', time.gmtime(value.duration))
             return 'Track %d: %s (%s)' % (value.order, value.name, duration)
 
-    class AlbumSerializer(serializer.ModelSerializer):
+    class AlbumSerializer(serializers.ModelSerializer):
         tracks = TrackListingField(many=True)
         
         class Meta:
@@ -295,13 +295,13 @@ Note that reverse relationships are not automatically generated by the `ModelSer
 
 **The following will not work:**
 
-    class AlbumSerializer(serializer.ModelSerializer):
+    class AlbumSerializer(serializers.ModelSerializer):
         class Meta:
             fields = ('tracks', ...) 
            
 Instead, you must explicitly add it to the serializer.  For example:
 
-    class AlbumSerializer(serializer.ModelSerializer):
+    class AlbumSerializer(serializers.ModelSerializer):
         tracks = serializers.PrimaryKeyRelationship(many=True)
         ...
 
@@ -315,7 +315,7 @@ The best way to ensure this is typically to make sure that the relationship on t
 
 Alternatively, you can use the `source` argument on the serializer field, to use a different accessor attribute than the field name.  For example.
 
-    class AlbumSerializer(serializer.ModelSerializer):
+    class AlbumSerializer(serializers.ModelSerializer):
         tracks = serializers.PrimaryKeyRelationship(many=True, source='track_set')
 
 See the Django documentation on [reverse relationships][reverse-relationships] for more details.