docs: Fix up HTML links to proper reST links.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@171382 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/LibASTMatchers.rst b/docs/LibASTMatchers.rst
index 56a1a7f..738de79 100644
--- a/docs/LibASTMatchers.rst
+++ b/docs/LibASTMatchers.rst
@@ -7,9 +7,9 @@
 :doc:`LibTooling`, LibASTMatchers helps to write code-to-code transformation
 tools or query tools.
 
-We assume basic knowledge about the Clang AST.  See the `Introduction to the
-Clang AST <IntroductionToTheClangAST.html>`_ if you want to learn more about
-how the AST is structured.
+We assume basic knowledge about the Clang AST.  See the :doc:`Introduction
+to the Clang AST <IntroductionToTheClangAST>` if you want to learn more
+about how the AST is structured.
 
 ..  FIXME: create tutorial and link to the tutorial
 
@@ -52,7 +52,7 @@
 
 The precondition to using the matchers is to understand how the AST for what you
 want to match looks like.  The
-`Introduction to the Clang AST <IntroductionToTheClangAST.html>`_ teaches you
+:doc:`Introduction to the Clang AST <IntroductionToTheClangAST>` teaches you
 how to dump a translation unit's AST into a human readable format.
 
 ..  FIXME: Introduce link to ASTMatchersTutorial.html