Merge pull request #17 from shawnps/patch-4

fix typo
diff --git a/hash.go b/hash.go
index cdd4192..a0420c1 100644
--- a/hash.go
+++ b/hash.go
@@ -19,7 +19,7 @@
 	NIL            = Parse("00000000-0000-0000-0000-000000000000")
 )
 
-// NewHash returns a new UUID dervied from the hash of space concatenated with
+// NewHash returns a new UUID derived from the hash of space concatenated with
 // data generated by h.  The hash should be at least 16 byte in length.  The
 // first 16 bytes of the hash are used to form the UUID.  The version of the
 // UUID will be the lower 4 bits of version.  NewHash is used to implement