tools: update dnc readme

Change-Id: I1009cfd1ed1230e19eee9462200b5d179b6ef5fa

tools/dnc/README.md

@@ -52,7 +52,7 @@ Then, launch the dnc service:
 ```shell
 systemctl start dnc.service
 ```
-Obtain the server identifier with the following command:
+Obtain the user identifier with the following command:
 ```shell
 dhtnet-crtmgr -g -p <privateKey_path> -c <cert_path>
 ```