topology2: add split topologies description

Describe what are split topologies and how to create it.

Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>

Author: bardliao

developer_guides/topology2/topology2.rst

@@ -1332,6 +1332,38 @@ You can use the ``-P`` switch to convert a 2.0 configuration file to the 1.0 con
 
    alsatplg <-D args=values> -P input.conf -o output.conf
 
+Split topologies
+****************
+
+Linux kernel can load multiple topologies, a topology for a single function.
+This feature is useful when a single device is disabled in specific productuds. To achieve this, you need to split
+the topology into multiple tplg files. The split topology files should be named as follows:
+
+.. code-block:: bash
+
+        sof-<platform>-<function>-id<BE id number>.tplg
+
+For example
+
+.. code-block:: bash
+
+        sof-arl-sdca-2amp-id2.tplg
+        sof-arl-sdca-mic-id4.tplg
+        sof-arl-dmic-2ch-id5.tplg
+        sof-arl-sdca-hdmi-id7.tgpl
+
+The split topologies are the subset of the monolithic topology. Usually, you just need to add a description with proper
+macro settings to disable the features that you don't need and set the first BE ID that in the topology in the cmake file
+to generate the split topologies.
+
+For example
+
+.. code-block:: bash
+
+        "cavs-sdw\;sof-arl-sdca-2amp-id2\;PLATFORM=mtl,NUM_SDW_AMP_LINKS=2,SDW_JACK=false,\
+        SDW_AMP_FEEDBACK=false,SDW_SPK_STREAM=Playback-SmartAmp,NUM_HDMIS=0"
+
+
 Topology reminders
 ******************