fix for etcd-io#19066 Print warnings when deprecated options are conf…

…igured in config file

server/config/config.go

@@ -234,6 +234,8 @@ func (c *ServerConfig) VerifyBootstrap() error {
 // VerifyJoinExisting sanity-checks the initial config for join existing cluster
 // case and returns an error for things that should never happen.
 func (c *ServerConfig) VerifyJoinExisting() error {
+	// The member has announced its peer urls to the cluster before starting; no need to
+	// set the configuration again.
 	if err := c.hasLocalMember(); err != nil {
 		return err
 	}