modify log level and update note

License: MIT
Signed-off-by: Kejie Zhang <601172892@qq.com>

core/bootstrap.go

@@ -118,7 +118,7 @@ func bootstrapRound(ctx context.Context, host host.Host, cfg BootstrapConfig) er
 	// sure we remain observant of changes to client configuration.
 	peers := cfg.BootstrapPeers()
 	if len(peers) == 0 {
-		log.Warning("no bootstrap in the configuration file")
+		log.Error("no bootstrap nodes configured: go-ipfs may have difficulty connecting to the network")
 	}
 	// determine how many bootstrap connections to open
 	connected := host.Network().Peers()