Fix typo in README

[boghicieusebiu]

No description provided.

[rlbdv]

Thanks. Would you mind adding a "Signed-off-by:" header to the patch? For the meaning and several ways to add it, see

bup/HACKING

Lines 94 to 117 in d9842e9

	Submitting patches
	==================
	As mentioned, all patches should be posted to the mailing list for
	review, and must be "signed off" by the author before official
	inclusion (see ./SIGNED-OFF-BY). You can create a "signed off" set of
	patches in ./patches, ready for submission to the list, like this:
	git format-patch -s -o patches origin/master
	which will include all of the patches since origin/master on your
	current branch. Then you can send them to the list like this:
	git send-email --to bup-list@googlegroups.com --compose patches/*
	The use of --compose will cause git to ask you to edit a cover letter
	that will be sent as the first message.
	It's also possible to handle everything in one step:
	git send-email -s --to bup-list@googlegroups.com --compose origin/master
	and you can add --annotate if you'd like to review or edit each patch
	before it's sent.

[boghicieusebiu]

I quickly edited the file from github. I haven't used git send-email so far. Feel free to decline the pull request if it does not fit the submitting format.