Merge pull request ruby-grape#670 from qqshfox/patch-1

fix a small typo in README.md

Author: dm1try

README.md

@@ -1332,7 +1332,7 @@ module API
       expose :user_name
       expose :text, documentation: { type: "string", desc: "Status update text." }
       expose :ip, if: { type: :full }
-      expose :user_type, user_id, if: lambda { |status, options| status.user.public? }
+      expose :user_type, :user_id, if: lambda { |status, options| status.user.public? }
       expose :digest { |status, options| Digest::MD5.hexdigest(status.txt) }
       expose :replies, using: API::Status, as: :replies
     end