gpg verify instructions don't work about butane

[sgreene570]

#11 fixed the ordering of the signature file in the readme, so you are correct about needing to flip the two files.
To resolve that public key, try running gpg2 --receive-keys 9CEB8FE6B4F1E9E752F61C82CDDE268EBB729EC7

[sgreene570]

also make sure you have imported the CoreOS application public signing key from here

http://coreos.com/security/

[kparal]

OK, thanks. It might be a good idea to link this in the doc, because a lot of people will have no idea about these prerequisite steps.