Refactor Autodeploy docs
Refactor Autodeploy docs

- Add a how it works section where Herokuish is mentioned
- Make the notes more apparent
- Merge the postgres variables section with its parent

jirutka/gitlabhq,dreampet/gitlab,jirutka/gitlabhq,iiet/iiet-git,mmkassem/gitlabhq,stoplightio/gitlabhq,jirutka/gitlabhq,mmkassem/gitlabhq,dreampet/gitlab,stoplightio/gitlabhq,axilleas/gitlabhq,axilleas/gitlabhq,axilleas/gitlabhq,jirutka/gitlabhq,stoplightio/gitlabhq,iiet/iiet-git,dreampet/gitlab,mmkassem/gitlabhq,axilleas/gitlabhq,iiet/iiet-git,stoplightio/gitlabhq,dreampet/gitlab,mmkassem/gitlabhq,iiet/iiet-git