[nrf fromtree] doc: release: Add notes for Bluetooth ECDH changes

Mention the removed prompt for BT_ECC in the migration guide, and also add
a note about the removed HCI emulation layer to the release notes.

Signed-off-by: Johan Hedberg <[email protected]>
(cherry picked from commit b3c6151)

Author: jhedberg

doc/releases/migration-guide-4.1.rst

@@ -344,6 +344,9 @@ Bluetooth Host
   makes a device vulnerable for downgrade attacks. If an application still needs to use LE legacy
   pairing, it should disable :kconfig:option:`CONFIG_BT_SMP_SC_PAIR_ONLY` manually.
 
+* The prompt for :kconfig:option:`CONFIG_BT_ECC` has been removed, since it only offers an internal
+  API, meaning internal users should explicitly select it in their respective Kconfig options.
+
 Bluetooth Crypto
 ================
 

doc/releases/release-notes-4.1.rst

@@ -96,6 +96,9 @@ Bluetooth
   * :kconfig:option:`CONFIG_BT_BUF_ACL_RX_COUNT` has been deprecated and
     :kconfig:option:`CONFIG_BT_BUF_ACL_RX_COUNT_EXTRA` has been added.
 
+  * The ECDH HCI command/event emulation layer has been removed, meaning the host will now always
+    do direct calls to PSA to perform these operations.
+
 * HCI Drivers
 
 * Mesh