[libc++] Reorganize the documentation of extensions for integral types

NOKEYCHECK=True
GitOrigin-RevId: 497705ff27b0216d08722671bc1c37df83b45aa5
diff --git a/docs/UsingLibcxx.rst b/docs/UsingLibcxx.rst
index 41d1737..626f388 100644
--- a/docs/UsingLibcxx.rst
+++ b/docs/UsingLibcxx.rst
@@ -424,6 +424,21 @@
 * ``to_integer``
 * ``to_underlying``
 
+Extended integral type support
+------------------------------
+
+Several platforms support types that are not specified in the Standard, such as
+the 128-bit integral types ``__int128_t`` and ``__uint128_t``. As an extension,
+libc++ does a best-effort attempt to support these types like other integral
+types, by supporting them notably in:
+
+* ``<bits>``
+* ``<charconv>``
+* ``<functional>``
+* ``<type_traits>``
+* ``<format>``
+* ``<random>``
+
 Additional types supported in random distributions
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -433,23 +448,6 @@
 ``geometric_distribution``, ``negative_binomial_distribution``, ``poisson_distribution``, and ``uniform_int_distribution``
 with ``int8_t``, ``__int128_t`` and their unsigned versions.
 
-Extended integral type support
-------------------------------
-
-Several platforms support the 128-bit integral types ``__int128_t`` and
-``__uint128_t``. When these types are present they can be used in the headers
-as required by the Standard:
-
-* ``<bits>``
-* ``<charconv>``
-* ``<functional>``
-* ``<type_traits>``
-
-As an extension these types can be used in the following headers:
-
-* ``<format>``
-* ``<random>``
-
 Extensions to ``<format>``
 --------------------------