doc: 54H EngB + C support drop

Updated docs to mention end of support for 54H20 EngB EngC.

Signed-off-by: Francesco Domenico Servidio <francesco.servidio@nordicsemi.no>

doc/nrf/releases_and_maturity/migration/migration_guide_2.9.rst

@@ -28,13 +28,42 @@ Required changes
 
 The following changes are mandatory to make your application work in the same way as in previous releases.
 
+nRF54H20
+========
+
+This section describes the changes specific to the nRF54H20 SoC and DK support in the |NCS|.
+For more information on changes related to samples and applications usage on the nRF54H20 DK, see :ref:`migration_2.9_required_nrf54h`.
+
+DK compatibility
+----------------
+
+.. toggle::
+
+  * The |NCS| v2.9.0 is compatible only with the following versions of the nRF54H20 DK, PCA10175: Engineering C - v0.8.3 and later revisions.
+    The nRF54H20 DK Engineering A and Engineering B (up to v0.8.2) are no longer compatible with the |NCS| v2.9.0.
+
+    Check the version number on your DK's sticker to verify its compatibility with the |NCS|.
+
+Dependencies
+------------
+
+The following required dependencies for the nRF54H20 SoC and DK have been updated.
+
+
 Samples and applications
 ========================
 
 This section describes the changes related to samples and applications.
 
 |no_changes_yet_note|
 
+.. _migration_2.9_required_nrf54h:
+
+nRF54H20
+--------
+
+|no_changes_yet_note|
+
 Libraries
 =========
 

doc/nrf/shortcuts.txt

@@ -262,5 +262,4 @@
 
 .. |filter_samples_by_board| replace:: If you want to list samples available for one or more specific boards, `use the nRF Connect for Visual Studio Code extension to filter them <Browse samples_>`_.
 
-.. |54H_engb_2_8| replace:: When using the nRF54H20 DK Engineering B (from v0.8.0 to 0.8.2), you must build samples and applications using the board revision 0.8.0 with the ``<board>@<revision>`` syntax.
-   For example, ``nrf54h20dk@0.8.0/nrf54h20/cpuapp`` when building for the application core, or ``nrf54h20dk@0.8.0/nrf54h20/cpurad`` when building for the radio core.
+.. |54H_engb_2_8| replace:: The nRF54H20 DK Engineering A and B (up to version 0.8.2) are no longer supported starting with |NCS| v2.9.0.