docs: reorder content in mem_alloc section

We should avoid hiding sections between long lists of API documentation.

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

@@ -121,14 +121,8 @@ generate a fatal LoadStoreError exception.
 
         To use the region above the 4MiB limit, you can use the :doc:`himem API</api-reference/system/himem>`.
 
-
-API Reference - Heap Allocation
--------------------------------
-
-.. include-build-file:: inc/esp_heap_caps.inc
-
 Thread Safety
-^^^^^^^^^^^^^
+-------------
 
 Heap functions are thread safe, meaning they can be called from different tasks simultaneously without any limitations.
 
@@ -143,11 +137,6 @@ The following features are documented on the :doc:`Heap Memory Debugging </api-r
 - :ref:`Heap Corruption Detection <heap-corruption>`
 - :ref:`Heap Tracing <heap-tracing>` (memory leak detection, monitoring, etc.)
 
-API Reference - Initialisation
-------------------------------
-
-.. include-build-file:: inc/esp_heap_caps_init.inc
-
 Implementation Notes
 --------------------
 
@@ -159,6 +148,18 @@ The heap capabilities allocator uses knowledge of the memory regions to initiali
 
 Calling ``free()`` involves finding the particular heap corresponding to the freed address, and then calling :cpp:func:`multi_heap_free` on that particular multi_heap instance.
 
+
+API Reference - Heap Allocation
+-------------------------------
+
+.. include-build-file:: inc/esp_heap_caps.inc
+
+
+API Reference - Initialisation
+------------------------------
+
+.. include-build-file:: inc/esp_heap_caps_init.inc
+
 .. _multi-heap:
 
 API Reference - Multi Heap API