Update getting-started.md
Update getting-started.md

Added an instruction to ignore the paket-files folder. Failing to do this can cause a lot of confusion for first time users of Paket.
I also added a section at the bottom about how to include Paket in the development process when working with other people.
thinkbeforecoding/Paket,vbfox/Paket,0x53A/Paket,0x53A/Paket,0x53A/Paket,vbfox/Paket,inosik/Paket,cloudRoutine/Paket,theimowski/Paket,fsprojects/Paket,NatElkins/Paket,theimowski/Paket,NatElkins/Paket,thinkbeforecoding/Paket,fsprojects/Paket,vbfox/Paket,baronfel/Paket,sergey-tihon/Paket,inosik/Paket,0x53A/Paket,sergey-tihon/Paket,jam40jeff/Paket,baronfel/Paket,jam40jeff/Paket,thinkbeforecoding/Paket,vbfox/Paket,NatElkins/Paket,cloudRoutine/Paket,cloudRoutine/Paket,cloudRoutine/Paket,NatElkins/Paket,thinkbeforecoding/Paket