dns_zone_check_period is available also with c-ares backend

diff --git a/doc/config.rst b/doc/config.rst
index 4239ae2a4334c7676e22ca47caada7e1e4c6f0c5..3c7ac3634be5638833b410d1ddea5fba79be4cb6 100644 (file)
--- a/doc/config.rst
+++ b/doc/config.rst
@@ -534,7 +534,7 @@ If it notices changes, all hostnames under that zone
 are looked up again.  If any host ip changes, it's connections
 are invalidated.
 
-Works only with UDNS backend (``--with-udns`` to configure).
+Works only with UDNS and c-ares backends (``--with-udns`` or ``--with-cares`` to configure).
 
 Default: 0.0 (disabled)