Add usage examples

[tomcontileslie]

Have a part of the README (or the Wiki) just have a list of a load of command line usage examples. Start by saying you should add

alias tc="python3 ~/path/to/ThatChord/thatchord.py"

to your .rc, and then give examples like

tc -h
# get help

tc Cmaj7
# output a Cmaj7 diagram for your default instrument

tc -i guitar -r guitar "D11(b5)"
# punctually change instrument

tc -f text -o print F
# print chord to command line

tc -f text -o print "F:2"
# didn't like the way it suggested playing F, try the second

tc "Cm@4"
# how do I play Cm way up on the frets?