[docs] Convert docs index page into Sphinx.

- Work in progress, this is mostly important because it lets us incrementally migrate the remaining documentation.
 - Lots of styling, editing, and integration work yet to come…
 - PR12589

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155133 91177308-0d34-0410-b5e6-96231b3b80d8

docs/mailing_lists.rst

@@ -0,0 +1,35 @@
+.. _mailing_lists:
+
+Mailing Lists
+=============
+
+ * `LLVM Announcements List
+   <http://lists.cs.uiuc.edu/mailman/listinfo/llvm-announce>`_
+
+   This is a low volume list that provides important announcements regarding
+   LLVM.  It gets email about once a month.
+
+ * `Developer's List <http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev>`_
+
+   This list is for people who want to be included in technical discussions of
+   LLVM. People post to this list when they have questions about writing code
+   for or using the LLVM tools. It is relatively low volume.
+
+ * `Bugs & Patches Archive <http://lists.cs.uiuc.edu/pipermail/llvmbugs/>`_
+
+   This list gets emailed every time a bug is opened and closed, and when people
+   submit patches to be included in LLVM.  It is higher volume than the LLVMdev
+   list.
+
+ * `Commits Archive <http://lists.cs.uiuc.edu/pipermail/llvm-commits/>`_
+
+   This list contains all commit messages that are made when LLVM developers
+   commit code changes to the repository. It is useful for those who want to
+   stay on the bleeding edge of LLVM development. This list is very high volume.
+
+ * `Test Results Archive
+   <http://lists.cs.uiuc.edu/pipermail/llvm-testresults/>`_
+
+   A message is automatically sent to this list by every active nightly tester
+   when it completes.  As such, this list gets email several times each day,
+   making it a high volume list.