doc: boards: amlogic: Add documentation on pre-generated FIP files

It add documentation on licencing & provides links to the amlogic-boot-fip
pre-built files collections.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
diff --git a/doc/board/amlogic/beelink-gtking.rst b/doc/board/amlogic/beelink-gtking.rst
index 56ce2cb..2fb50c5 100644
--- a/doc/board/amlogic/beelink-gtking.rst
+++ b/doc/board/amlogic/beelink-gtking.rst
@@ -44,6 +44,8 @@
 NB: Beelink use a common board config for GT-King, GT-King Pro and the
 GS-King-X model, hence the "beelink-s922x" name.
 
+For simplified usage, pleaser refer to :doc:`pre-generated-fip` with codename `beelink-s922x`
+
 .. code-block:: bash
 
     $ wget https://github.com/LibreELEC/amlogic-boot-fip/archive/master.zip