updated readme with explanations of technologies

Cool. Maybe just "Foreman is an open source project that gives system administrators the power to easily automate repetitive tasks." The main issue was that as we were going through the README sequentially, we didn't know: what is foreman and why someone would use 'foreman start' instead of 'rails s'? Why is it necessary? Also, FYI, typo in line 90 "develop"