Update documentation from PEP 757

Remove doc from the header file, only keep doc in Doc/c-api/long.rst
to avoid the documentation to be outdated in one place.

Author: vstinner

Doc/c-api/long.rst

@@ -724,7 +724,7 @@ Export API
 
    .. c:member:: uint8_t negative
 
-      1 if the number is negative, 0 otherwise.
+      ``1`` if the number is negative, ``0`` otherwise.
       Only valid if :c:member:`digits` is not ``NULL``.
 
    .. c:member:: Py_ssize_t ndigits
@@ -741,11 +741,11 @@ Export API
 
    Export a Python :class:`int` object.
 
-   On success, set *\*export_long* and return 0.
-   On error, set an exception and return -1.
+   On success, set *\*export_long* and return ``0``.
+   On error, set an exception and return ``-1``.
 
-   If *export_long.digits* is not ``NULL``, :c:func:`PyLong_FreeExport` must be
-   called when the export is no longer needed.
+   If *export_long->digits* is not ``NULL``, :c:func:`PyLong_FreeExport` must
+   be called when the export is no longer needed.
 
 
 .. c:function:: void PyLong_FreeExport(PyLongExport *export_long)
@@ -794,6 +794,9 @@ The :c:type:`PyLongWriter` API can be used to import an integer.
    On success, return a Python :class:`int` object.
    On error, set an exception and return ``NULL``.
 
+   The function takes care of normalizing the digits and converts the object
+   to a compact integer if needed.
+
 
 .. c:function:: void PyLongWriter_Discard(PyLongWriter *writer)
 

Include/cpython/longintrepr.h

@@ -142,20 +142,9 @@ _PyLong_CompactValue(const PyLongObject *op)
 /* --- Import/Export API -------------------------------------------------- */
 
 typedef struct PyLongLayout {
-    // Bits per digit
     uint8_t bits_per_digit;
-
-    // Digit size in bytes
     uint8_t digit_size;
-
-    // Digits order:
-    // * 1 for most significant digit first
-    // * -1 for least significant first
     int8_t digits_order;
-
-    // Digit endianness:
-    // * 1 for most significant byte first (big endian)
-    // * -1 for least significant first (little endian)
     int8_t endianness;
 } PyLongLayout;