docs: update FAQ on secondary controllers (#7190)

docs/getting-started/faq.md

@@ -2,12 +2,20 @@
 
 ## Does Z-Wave JS support secondary controllers?
 
-Yes and no.
+Mostly.
 
-Z-Wave JS expects to **be the primary controller** in the network and it will try to assume that role when started. It will not work correctly as a secondary controller.
+Slightly longer answer:\
+On startup, Z-Wave JS detects whether the Z-Wave module it controls is a primary controller or a secondary/inclusion controller.
 
-It does however support **having secondary controllers in the network**. This includes:
+Its default operation mode is acting as a **primary controller**, or assuming that role if there is none in the network. In this mode, it supports **having secondary controllers in the network**. This includes:
 
 - Including/excluding a secondary controller
 - Letting secondary controllers (inclusion controllers) include and exclude devices
 - Perform network key exchange with devices included by a secondary controller
+
+Z-Wave JS also supports joining other networks as a **secondary controller**. This mode is not meant for controlling a smart home, because reports are sent to the primary controller.
+
+> [!WARNING] Secondary controller support is still experimental and has some limitations:
+>
+> - Including devices on behalf of the primary controller does not work
+> - Devices won't be interviewed by default. Triggering an interview manually may set up the lifelines incorrectly.