chore: update example

Author: vmihailenco

example/otel/README.md

@@ -40,6 +40,9 @@ UPTRACE_DSN=http://project2_secret_token@localhost:14317/2 go run client.go
 trace: http://localhost:14318/traces/ee029d8782242c8ed38b16d961093b35
 ```
 
+You can also open Uptrace UI at [http://localhost:14318](http://localhost:14318) to view available
+spans, logs, and metrics.
+
 ## Links
 
 - [Uptrace open-source APM](https://uptrace.dev/get/open-source-apm.html)