Add spanish tranlation for cheat sheet introduction
Update :es: translation
Improve grammar
Update add command description
Fix markdown heading missing space
Merge branch 'master' into cheat-sheet-es-adjustments

Conflicts:
	downloads/es_ES/github-git-cheat-sheet.md
Renamed over the top of master
Merge pull request #143 from github/cheat-sheet-es-adjustments

Cheat sheet ES adjustments