Fix typo

Signed-off-by: Thane Thomson <connect@thanethomson.com>

types/vote.go

@@ -86,7 +86,7 @@ func (vote *Vote) CommitSig() CommitSig {
 }
 
 // VoteSignBytes returns the proto-encoding of the canonicalized Vote, for
-// signing. Panics is the marshaling fails.
+// signing. Panics if the marshaling fails.
 //
 // The encoded Protobuf message is varint length-prefixed (using MarshalDelimited)
 // for backwards-compatibility with the Amino encoding, due to e.g. hardware