Merge pull request #628 from sachse/readme-fix

Readme typo fixes

Author: steveklabnik

README.md

@@ -521,7 +521,7 @@ to `comments` underneath a `links` key:
 class PostSerializer < ActiveModel::Serializer
   attributes :id, :title, :body
 
-  has_many :comments, embed: ids, embed_namespace: :links
+  has_many :comments, embed: :ids, embed_namespace: :links
 end
 ```
 
@@ -612,7 +612,7 @@ the root document (say, `linked`), you can specify an `embed_in_root_key`:
 
 ```ruby
 class PostSerializer < ActiveModel::Serializer
-  embed: ids, include: true, embed_in_root_key: :linked
+  embed :ids, include: true, embed_in_root_key: :linked
 
   attributes: :id, :title, :body
   has_many :comments, :tags