x/crypto/ssh: fix comment

Fixes golang/go#11603

Change-Id: I019af73f5e036b47b8bd6c4a5541c06b97b44f11
Reviewed-on: https://go-review.googlesource.com/11866
Reviewed-by: Andrew Gerrand <adg@golang.org>

ssh/connection.go

@@ -33,7 +33,7 @@ type ConnMetadata interface {
 	// into the session ID.
 	ClientVersion() []byte
 
-	// ServerVersion returns the client's version string as hashed
+	// ServerVersion returns the server's version string as hashed
 	// into the session ID.
 	ServerVersion() []byte