Update ServerOptions.java

Author: MingzhenHan

hugegraph-server/hugegraph-api/src/main/java/org/apache/hugegraph/config/ServerOptions.java

@@ -42,7 +42,7 @@ public static synchronized ServerOptions instance() {
     public static final ConfigOption<String> REST_SERVER_URL =
             new ConfigOption<>(
                     "restserver.url",
-                    "The url for listening of hugeserver.",
+                    "The url for listening of graph server.",
                     disallowEmpty(),
                     "http://127.0.0.1:8080"
             );