add intial README.md for git tutorial
ignore temporary vim files (*.swp)
spelling
always italicise master
italicise heads
use correct head name
bold any to differentiate between heads
clarify updating of HEAD when making a commit
include link about log messages
discuss forking repos
clarify pulling
generalise
use <remote> instead of <remote-repo>
add bullets for example commands
push branch to a general remote
document -u option to git push
push tags to general remote