docs: Alphbetically sort toctree

This commit sorts the entries of variuos toctrees
alphabetically. Indentation was also fixed. The order
of some toctrees were not modified if the existing
order had some form of suggested reading order.

docs/en/api-reference/system/index.rst

@@ -2,29 +2,29 @@ System API
 **********
 
 .. toctree::
-   :maxdepth: 1
+    :maxdepth: 1
 
-   FreeRTOS <freertos>
-   FreeRTOS Additions <freertos_additions>
-   Heap Memory Allocation <mem_alloc>
-   Heap Memory Debugging <heap_debug>
-   Himem (large external SPI RAM) API <himem>
-   Interrupt Allocation <intr_alloc>
-   Watchdogs <wdts>
-   eFuse Manager <efuse>
-   Inter-Processor Call <ipc>
-   High Resolution Timer <esp_timer>
-   Logging <log>
-   Event Loop Library <esp_event>
-   Application Level Tracing <app_trace>
-   Power Management <power_management>
-   Sleep Modes <sleep_modes>
-   Over The Air Updates (OTA) <ota>
-   ESP HTTPS OTA <esp_https_ota>
-   ESP pthread <esp_pthread>
-   Error Codes and Helper Functions <esp_err>
-   App image format <app_image_format>
-   Miscellaneous System APIs <system>
+    App image format <app_image_format>
+    Application Level Tracing <app_trace>
+    eFuse Manager <efuse>
+    Error Codes and Helper Functions <esp_err>
+    ESP HTTPS OTA <esp_https_ota>
+    ESP pthread <esp_pthread>
+    Event Loop Library <esp_event>
+    FreeRTOS <freertos>
+    FreeRTOS Additions <freertos_additions>
+    Heap Memory Allocation <mem_alloc>
+    Heap Memory Debugging <heap_debug>
+    High Resolution Timer <esp_timer>
+    Himem (large external SPI RAM) API <himem>
+    Inter-Processor Call <ipc>
+    Interrupt Allocation <intr_alloc>
+    Logging <log>
+    Miscellaneous System APIs <system>
+    Over The Air Updates (OTA) <ota>
+    Power Management <power_management>
+    Sleep Modes <sleep_modes>
+    Watchdogs <wdts>
 
 
 Code examples for this API section are provided in the :example:`system` directory of ESP-IDF examples.