Extending documentation in config.sample.php for `trusted_proxies`

Signed-off-by: Oliver Wegner <void1976@gmail.com>

config/config.sample.php

@@ -1499,11 +1499,26 @@ $CONFIG = array(
 /**
  * List of trusted proxy servers
  *
- * If you configure these also consider setting `forwarded_for_headers` which
- * otherwise defaults to `HTTP_X_FORWARDED_FOR` (the `X-Forwarded-For` header).
+ * You may set this to an array containing a combination of
+ * - IPv4 addresses, e.g. `192.168.2.123`
+ * - IPv4 ranges in CIDR notation, e.g. `192.168.2.0/24`
+ * - IPv6 addresses, e.g. `fd9e:21a7:a92c:2323::1`
+ *
+ * _(CIDR notation for IPv6 is currently work in progress and thus not
+ * available as of yet)_
+ *
+ * When an incoming request's `REMOTE_ADDR` matches any of the IP addresses
+ * specified here, it is assumed to be a proxy instead of a client. Thus, the
+ * client IP will be read from the HTTP header specified in
+ * `forwarded_for_headers` instead of from `REMOTE_ADDR`.
+ *
+ * So if you configure `trusted_proxies`, also consider setting
+ * `forwarded_for_headers` which otherwise defaults to `HTTP_X_FORWARDED_FOR`
+ * (the `X-Forwarded-For` header).
+ *
  * Defaults to an empty array.
  */
-'trusted_proxies' => array('203.0.113.45', '198.51.100.128'),
+'trusted_proxies' => array('203.0.113.45', '198.51.100.128', '192.168.2.0/24'),
 
 /**
  * Headers that should be trusted as client IP address in combination with