README.md in google_sign_in-1.1.2 vs README.md in google_sign_in-1.2.0

@@ -62,11 +62,21 @@
 end
 ```
 
 **⚠️ Important:** Take care to protect your client secret from disclosure to third parties.
 
+9. (Optional) The callback route can be configured using:
 
+```ruby
+# config/initializers/google_sign_in.rb
+Rails.application.configure do
+  config.google_sign_in.root = "my_own/google_sign_in_route"
+end
+```
+
+Which would make the callback `/my_own/google_sign_in_route/callback`.
+
 ## Usage
 
 This gem provides a `google_sign_in_button` helper. It generates a button which initiates Google sign-in:
 
 ```erb
@@ -78,11 +88,12 @@
   Sign in with my <%= image_tag('google_logo.png', alt: 'Google') %> account
 <% end %>
 ```
 
 The `proceed_to` argument is required. After authenticating with Google, the gem redirects to `proceed_to`, providing
-a Google ID token in `flash[:google_sign_in_token]`. Your application decides what to do with it:
+a Google ID token in `flash[:google_sign_in][:id_token]` or an [OAuth authorizaton code grant error](https://tools.ietf.org/html/rfc6749#section-4.1.2.1)
+in `flash[:google_sign_in][:error]`. Your application decides what to do with it:
 
 ```ruby
 # config/routes.rb
 Rails.application.routes.draw do
   # ...
@@ -106,12 +117,15 @@
     end
   end
 
   private
     def authenticate_with_google
-      if flash[:google_sign_in_token].present?
-        User.find_by google_id: GoogleSignIn::Identity.new(flash[:google_sign_in_token]).user_id
+      if id_token = flash[:google_sign_in][:id_token]
+        User.find_by google_id: GoogleSignIn::Identity.new(id_token).user_id
+      elsif error = flash[:google_sign_in][:error]
+        logger.error "Google authentication error: #{error}"
+        nil
       end
     end
 end
 ```
 
@@ -140,9 +154,13 @@
 * `avatar_url`
 
 * `locale`
 
 * `hosted_domain`: The user’s hosted G Suite domain, provided only if they belong to a G Suite.
+
+* `given_name`: The user's given name.
+
+* `last_name`: The user's last name.
 
 
 ## Security
 
 For information on our security response procedure, see [SECURITY.md](SECURITY.md).