ssh: fixing a small typo in connection.go

Change-Id: Iffbed7e16a8bb32c5ff7c393f3b6ad7dcffc69ac
Reviewed-on: https://go-review.googlesource.com/44340
Reviewed-by: Han-Wen Nienhuys <hanwen@google.com>
Run-TryBot: Han-Wen Nienhuys <hanwen@google.com>

ssh/connection.go

@@ -25,7 +25,7 @@ type ConnMetadata interface {
 	// User returns the user ID for this connection.
 	User() string
 
-	// SessionID returns the sesson hash, also denoted by H.
+	// SessionID returns the session hash, also denoted by H.
 	SessionID() []byte
 
 	// ClientVersion returns the client's version string as hashed