docs(guide/Scopes): (fix) gramatical error line 248

changed "as well as it guarantees"    to   ", and guarantees"

![screen shot 2014-10-29 at 11 44 23 am](https://cloud.githubusercontent.com/assets/4251807/4832425/0beb8740-5f9c-11e4-9e2c-ccad1d76050d.png)

before:

 
![screen shot 2014-10-29 at 11 48 12 am](https://cloud.githubusercontent.com/assets/4251807/4832451/43f6f46c-5f9c-11e4-83d0-708e9bbe9793.png)