feat(edgeai): Add a guide on EdgeAI memory carveout overlay

* From SDK 11.1, the EdgeAI memory carveouts are maintained as a
separate overlay - k3-am62a7-sk-edgeai.dtbo
Hence, add an FAQ for users on the same

* While at it, also fix the faq.rst to follow guidelines
for section headers as per [0]

[0]: https://www.sphinx-doc.org/en/master/usage/restructuredtext/basics.html#sections

Signed-off-by: Chirag Shilwant <[email protected]>

Author: cshilwant

source/devices/AM62AX/edgeai/faq.rst

@@ -1,13 +1,67 @@
 .. _pub_edgeai_FAQs:
 
-====
+####
 FAQs
-====
+####
+
+.. _pub_edgeai_overlay:
+
+*****************************************************************************************************************************************
+Why does "ERROR: Unable to map memory @ 0xa2000000..." appear after applying a custom DTBO using name_overlays from SDK 11.1 with EdgeAI?
+*****************************************************************************************************************************************
+
+Background
+==========
+
+Starting with Processor SDK 11.1, the :file:`k3-am62a7-sk-edgeai.dtbo` overlay is automatically applied by default in the AM62A board environment (``ti-u-boot``).
+This is set via the ``name_overlays`` variable in U-Boot, as seen in `board/ti/am62ax/am62ax.env <https://git.ti.com/cgit/ti-u-boot/ti-u-boot/tree/board/ti/am62ax/am62ax.env?h=11.01.05#n22>`__
+
+Issue
+=====
+
+If you add or override overlays using :file:`uEnv.txt` (e.g. for enabling IMX219 camera support), you may unintentionally replace the default ``name_overlays`` value.
+This means the essential EdgeAI memory carve-out overlay (:file:`k3-am62a7-sk-edgeai.dtbo`) is no longer applied.
+As a result, EdgeAI applications may fail to allocate memory, showing errors such as:
+
+.. code-block:: console
+
+   APP_LOG: ERROR: Unable to map memory @ 0xa2000000 of size 3288576 bytes !!!
+
+Who is affected?
+================
+
+EdgeAI users upgrading to SDK 11.1 (or newer) who apply custom device tree overlays and do not re-apply the EdgeAI carve-out overlay.
+
+Solution
+========
+
+Always include :file:`k3-am62a7-sk-edgeai.dtbo` in your overlays when customizing ``name_overlays`` in :file:`uEnv.txt` or at the U-Boot prompt.
+For example - To enable IMX219 camera support
+
+.. code-block:: console
+
+   name_overlays=ti/k3-am62a7-sk-edgeai.dtbo ti/k3-am62x-sk-csi2-imx219.dtbo
+
+This ensures the memory region required by EdgeAI applications is reserved.
+
+Summary Table
+-------------
+
+.. csv-table:: Summary
+   :header: "SDK Version","Default EdgeAI Overlay","Action Needed When Customizing Overlays"
+
+   "≤ 10.1", "None", "Only add your required overlays"
+   "≥ 11.1", "EdgeAI overlay applied", "Must re-apply EdgeAI overlay when overriding `name_overlays`"
+
+.. tip::
+
+   If you encounter memory mapping errors after customizing overlays, verify that the EdgeAI carve-out overlay is present in your configuration.
 
 .. _pub_edgeai_multiple_usb_cams:
 
+*****************************************************************************
 Getting Error when trying to capture from multiple USB cameras simultaneously
-=============================================================================
+*****************************************************************************
 
 This is a common issue faced in the industry with many USB cameras.
 You may get errors like ``Failed to allocate required memory.`` when tying to