Spellchecks, feedback form and bug fixes

Fixed some spelling and added a feedback form. Also updated the description on how to detect the appropriate port to connect the Arduino in Linux OS. Stopped at Chapter 5.
![dexter](https://f.cloud.github.com/assets/1539420/338548/39d9dde4-9d17-11e2-9441-bcaf1d4bb1d5.gif)