doc: Add preliminary tutorial section on sync/pr
This is still a bit of a work in progress, I still need to add a bit
about using semaphores to keep the program running at the end. (I'm
actually running into an issue with that when using sync/pr
though,
so I'll reach out about that in either an issue or IRC.) Figured I'd
get this up at least though so you can see it!
Edited by Jonathan Frederickson