doc: document new reload:script support

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

doc/config.md

@@ -913,9 +913,17 @@ configurable with the following options:
     endless restarts.  Useful in many use-cases, but not what `service`
     was originally designed for so not the default behavior
   * `oncrash:reboot` -- when all retries have failed, and the service
-    has *crashed*, if this option is set the system is rebooted.
+    has *crashed*, if this option is set the system is rebooted
   * `oncrash:script` -- similarly, but instead of rebooting, call the
-    `post:script` action if set, see below.
+    `post:script` action with exit code `crashed`, see below
+  * `reload:script args` -- some services do not support `SIGHUP` but
+    may have other ways to update the configuration of a running daemon.
+    When `reload:script` is defined it is preferred over `SIGHUP`
+
+> [!CAUTION]
+> The `reload:script` is called in as PID 1, without any timeout!
+> Meaning, it is up to you to ensure this script is not blocking
+> for seconds at a time or never terminates.
 
 When stopping a service (run/task/sysv/service), either manually or when
 moving to another runlevel, Finit starts by sending `SIGTERM`, to allow