ssh: fix documentation on ServerConfig.PublicKeyCallback
Fix leftovers from the old days to match today's method signature.
Fixes golang/go#21325
Run-TryBot: Han-Wen Nienhuys
TryBot-Result: Gobot Gobot
@@ -67,7 +67,7 @@ type ServerConfig struct {
PasswordCallback func(conn ConnMetadata, password []byte) (*Permissions, error)
// PublicKeyCallback, if non-nil, is called when a client
- // offers a public key for authentication. It must return true
+ // offers a public key for authentication. It must return a nil error
// if the given public key can be used to authenticate the
// given user. For example, see CertChecker.Authenticate. A
// call to this function does not guarantee that the key
