Fixed what I think is a typo
Fixed what I think is a typo

Signed-off-by: Scott Chacon <81ce51881e261567723ba832f9c004d3d8116425@gmail.com>
schacon/whygitisbetter,paulcbetts/whygitisbetter,d2s/whygitisbetter,Br3nda/whygitisbetter,m-takagi/whygitisbetter