Corrected text to reflect new[er] process of specifying fingerprints instead of individual keys.

Author: Jeff Frontz

contrib/gitian-keys/README.md

@@ -1,9 +1,10 @@
 ## PGP keys of Gitian builders and Developers
 
-The keys.txt contains the public keys of Gitian builders and active developers.
+The file `keys.txt` contains fingerprints of the public keys of Gitian builders
+and active developers.
 
-The keys are mainly used to sign git commits or the build results of Gitian
-builds.
+The associated keys are mainly used to sign git commits or the build results
+of Gitian builds.
 
 The most recent version of each pgp key can be found on most pgp key servers.