message: Updated help for ledger custom command
diff: @@ -941,6 +941,7 @@ pub mod custom_command {
  .add_optional_param("sign", "Is signature required")
  .add_example(r#"ledger custom {"reqId":1,"identifier":"V4SGRU86Z58d6TV7PBUe6f","operation":{"type":"105","dest":"V4SGRU86Z58d6TV7PBUe6f"},"protocolVersion":2}"#)
  .add_example(r#"ledger custom {"reqId":2,"identifier":"V4SGRU86Z58d6TV7PBUe6f","operation":{"type":"1","dest":"VsKV7grR1BUE29mG2Fm2kX"},"protocolVersion":2} sign=true"#)
  + .add_example(r#"ledger custom context"#)
  .finalize()
  );
  