stats: fix capport_unique_ipv6 comment

src/capport/stats.py

@@ -75,7 +75,7 @@ async def amain(client_ifname: str):
         'capport_unique_ipv6',
         'gauge',
         len(unique_ipv6),
-        help='Number of IPv4 clients (unique per mac) in client network seen in neighbor cache',
+        help='Number of IPv6 clients (unique per mac) in client network seen in neighbor cache',
     )
     print_metric(
         'capport_total_ipv4',