heap: remove misleading info about malloc being equivalent to heap_ca…

…ps_malloc(p, MALLOC_CAP_8BIT)

The actual memory allocated for malloc() depends on a lot of factors, see heap_caps_malloc_default()

Closes #7659

components/heap/include/esp_heap_caps.h

@@ -58,8 +58,6 @@ esp_err_t heap_caps_register_failed_alloc_callback(esp_alloc_failed_hook_t callb
  *
  * Equivalent semantics to libc malloc(), for capability-aware memory.
  *
- * In IDF, ``malloc(p)`` is equivalent to ``heap_caps_malloc(p, MALLOC_CAP_8BIT)``.
- *
  * @param size Size, in bytes, of the amount of memory to allocate
  * @param caps        Bitwise OR of MALLOC_CAP_* flags indicating the type
  *                    of memory to be returned

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

@@ -30,7 +30,9 @@ For more details on these internal memory types, see :ref:`memory-layout`.
 
     It's also possible to connect external SPI RAM to the {IDF_TARGET_NAME} - :doc:`external RAM </api-guides/external-ram>` can be integrated into the {IDF_TARGET_NAME}'s memory map using the flash cache, and accessed similarly to DRAM.
 
-DRAM uses capability ``MALLOC_CAP_8BIT`` (accessible in single byte reads and writes). When calling ``malloc()``, the ESP-IDF ``malloc()`` implementation internally calls ``heap_caps_malloc(size, MALLOC_CAP_8BIT)`` in order to allocate DRAM that is byte-addressable. To test the free DRAM heap size at runtime, call cpp:func:`heap_caps_get_free_size(MALLOC_CAP_8BIT)`.
+DRAM uses capability ``MALLOC_CAP_8BIT`` (accessible in single byte reads and writes). To test the free DRAM heap size at runtime, call cpp:func:`heap_caps_get_free_size(MALLOC_CAP_8BIT)`.
+
+When calling ``malloc()``, the ESP-IDF ``malloc()`` implementation internally calls cpp:func:`heap_caps_malloc_default(size)`. This will allocate memory with capability ``MALLOC_CAP_DEFAULT``, which is byte-addressable.
 
 Because malloc uses the capabilities-based allocation system, memory allocated using :cpp:func:`heap_caps_malloc` can be freed by calling
 the standard ``free()`` function.