docs(bt/bluedroid): Added migration guide for bluedroid init API

Closes https://github.com/espressif/esp-idf/issues/15352

docs/en/migration-guides/release-5.x/5.2/bluetooth-classic.rst

@@ -0,0 +1,15 @@
+Bluetooth Classic
+=================
+
+:link_to_translation:`zh_CN:[中文]`
+
+Bluedroid
+---------
+- The following Bluedroid APIs have been changed:
+
+    - :component_file:`/bt/host/bluedroid/api/include/api/esp_bt_main.h`
+
+        - The function ``esp_bluedroid_init`` has been deprecated and replaced by ``esp_bluedroid_init_with_cfg``.
+        - A new configuration structure ``esp_bluedroid_config_t`` has been introduced as a parameter for ``esp_bluedroid_init_with_cfg``. The field ``ssp_en`` in this structure determines the pairing mode.
+
+- The configuration ``CONFIG_BT_SSP_ENABLED`` has been removed, as pairing mode can now be configured at runtime.

docs/en/migration-guides/release-5.x/5.2/index.rst

@@ -13,3 +13,4 @@ Migration from 5.1 to 5.2
     storage
     system
     :SOC_WIFI_SUPPORTED: wifi
+    bluetooth-classic

docs/zh_CN/migration-guides/release-5.x/5.2/bluetooth-classic.rst

@@ -0,0 +1,15 @@
+经典蓝牙
+=================
+
+:link_to_translation:`en:[English]`
+
+Bluedroid
+---------
+
+- 以下 Bluedroid API 发生变更
+    - :component_file:`/bt/host/bluedroid/api/include/api/esp_bt_main.h`
+
+        - 函数 ``esp_bluedroid_init`` 已被弃用，并由 ``esp_bluedroid_init_with_cfg`` 取代。
+        - 新增配置结构体 ``esp_bluedroid_config_t`` 作为 ``esp_bluedroid_init_with_cfg`` 的参数引入。该结构体中的 ``ssp_en`` 字段用于确定配对模式。
+
+- 配置选项 ``CONFIG_BT_SSP_ENABLED`` 已被移除，因为配对模式现在可以在运行时进行配置。

docs/zh_CN/migration-guides/release-5.x/5.2/index.rst

@@ -13,3 +13,4 @@
     storage
     system
     :SOC_WIFI_SUPPORTED: wifi
+    bluetooth-classic