[libcxx] Add ReleaseNotes.rst file for release notes

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@341550 91177308-0d34-0410-b5e6-96231b3b80d8

docs/ReleaseNotes.rst

@@ -0,0 +1,43 @@
+========================================
+Libc++ 8.0.0 (In-Progress) Release Notes
+========================================
+
+.. contents::
+   :local:
+   :depth: 2
+
+Written by the `Libc++ Team <http://libcxx.llvm.org>`_
+
+.. warning::
+
+   These are in-progress notes for the upcoming libc++ 8 release.
+   Release notes for previous releases can be found on
+   `the Download Page <http://releases.llvm.org/download.html>`_.
+
+Introduction
+============
+
+This document contains the release notes for the libc++ C++ Standard Library,
+part of the LLVM Compiler Infrastructure, release 8.0.0. Here we describe the
+status of libc++ in some detail, including major improvements from the previous
+release and new feature work. For the general LLVM release notes, see `the LLVM
+documentation <http://llvm.org/docs/ReleaseNotes.html>`_. All LLVM releases may
+be downloaded from the `LLVM releases web site <http://llvm.org/releases/>`_.
+
+For more information about libc++, please see the `Libc++ Web Site
+<http://libcxx.llvm.org>`_ or the `LLVM Web Site <http://llvm.org>`_.
+
+Note that if you are reading this file from a Subversion checkout or the
+main Libc++ web page, this document applies to the *next* release, not
+the current one. To see the release notes for a specific release, please
+see the `releases page <http://llvm.org/releases/>`_.
+
+What's New in Libc++ 8.0.0?
+===========================
+
+New Features
+------------
+
+API Changes
+-----------
+