move half of prework to later day
swap out github resources
update link for Mastering GitHub
Merge pull request #10 from cuny-nytech/prework-split

move half of prework to later day
Merge remote-tracking branch 'origin/master' into github-resource

Conflicts:
	docs/schedule.md
Merge pull request #13 from cuny-nytech/github-resource

swap out github resources
Merge remote-tracking branch 'origin/master' into student-dir

Conflicts:
	docs/schedule.md