[libc++][doc] Update the release notes.
Updates the libc++ release notes with the changes since the last
release.
Differential Revision: https://reviews.llvm.org/D95248
GitOrigin-RevId: 193cda105d9131de533596077ff0c694e8b87bbd
diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst
index 8ce9b29..696275e 100644
--- a/docs/ReleaseNotes.rst
+++ b/docs/ReleaseNotes.rst
@@ -37,8 +37,31 @@
New Features
------------
+- Random device support has been made optional. It's enabled by default and can
+ be disabled by building libc++ with ``-DLIBCXX_ENABLE_RANDOM_DEVICE=OFF``.
+ Disabling random device support can be useful when building the library for
+ platforms that don't have a source of randomness, such as some embedded
+ platforms. When this is not supported, most of ``<random>`` will still be
+ available, but ``std::random_device`` will not.
+- Localization support has been made optional. It's enabled by default and can
+ be disabled by building libc++ with ``-DLIBCXX_ENABLE_LOCALIZATION=OFF``.
+ Disabling localization can be useful when porting to platforms that don't
+ support the C locale API (e.g. embedded). When localization is not
+ supported, several parts of the library will be disabled: ``<iostream>``,
+ ``<regex>``, ``<locale>`` will be completely unusable, and other parts may be
+ only partly available.
+- If libc++ is compiled with a C++20 capable compiler it will be compiled in
+ C++20 mode. Else libc++ will be compiled in C++17 mode.
+- Several unqualified lookups in libc++ have been changed to qualified lookups.
+ This makes libc++ more ADL-proof.
+- The libc++ implementation status pages have been overhauled. Like other parts
+ documentation they now use restructured text instead of html. Starting with
+ libc++12 the status pages are part of libc++'s documentation.
+- More C++20 features have been implemented. :doc:`Cxx2aStatus` has the full
+ overview of libc++'s C++20 implementation status.
+- Work has started to implement new C++2b features. :doc:`Cxx2bStatus` has the
+ full overview of libc++'s C++2b implementation status.
-- ...
API Changes
-----------
diff --git a/docs/index.rst b/docs/index.rst
index ecece32..22d54fa 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -140,7 +140,7 @@
* :ref:`C++14 - Complete <cxx1y-status>`
* :ref:`C++17 - In Progress <cxx1z-status>`
* :ref:`C++20 - In Progress <cxx2a-status>`
-* :ref:`C++2b - Not Started <cxx2b-status>`
+* :ref:`C++2b - In Progress <cxx2b-status>`
* `Post C++14 Technical Specifications - In Progress <http://libcxx.llvm.org/ts1z_status.html>`__
* :ref:`C++ Feature Test Macro Status <feature-status>`
