Fix developer key manual generation doc

the current code doesn't work because of the attr_accessible on
DeveloperKey

Change-Id: Id6cf7a3eab5808c05c22c43e6095ab6011ec0f76
Reviewed-on: https://gerrit.instructure.com/12275
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Zach Pendleton <zachp@instructure.com>

Author: codekitchen

doc/api/oauth.md

@@ -52,11 +52,12 @@ client\_secret for your application. There isn't yet any UI for
 generating these keys, so you will need to generate an API key from the Rails console:
 
     $ script/console
-    > key = DeveloperKey.create!(
-        :email => 'your_email',
-        :user_name => 'your name',
-        :account => Account.default)
-    > puts "client_id: #{key.id} client_secret: #{key.api_key}"
+    > key = DeveloperKey.create! { |k|
+        k.email = 'your_email'
+        k.user_name = 'your name'
+        k.account = Account.default
+      }
+    > puts "client_id: #{key.global_id} client_secret: #{key.api_key}"
 
 Web Application Flow
 --------------------