Style fixes
Style fixes

- Introduce acronym for GDS
- Use the serial/Oxford comma
- Add a comma for readability
- Hyphenation where appropriate

ajstarks/gopheracademy-web,mem/gopheracademy-web,derekcollison/gopheracademy-web,raphael/gopheracademy-web,mitchellh/gopheracademy-web,tv42/gopheracademy-web,derekcollison/gopheracademy-web,derekparker/gopheracademy-web,mem/gopheracademy-web,raphael/gopheracademy-web,spf13/gopheracademy-web,spf13/gopheracademy-web