DOCS: added some secs to getting_started
DOCS: added some secs to getting_started

villrv/MOSFiT,guillochon/MOSFiT,guillochon/MOSFiT,mnicholl/MOSFiT,guillochon/MOSFiT,guillochon/FriendlyFit,mnicholl/MOSFiT,villrv/MOSFiT,bmockler/MOSFiT,mnicholl/MOSFiT,bmockler/MOSFiT