Added table of contents declaration in CommandLine Library documentation.

Contributed-by:  Dan Liew <daniel.liew@imperial.ac.uk>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180919 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/CommandLine.rst b/docs/CommandLine.rst
index 073958b..ea0c369 100644
--- a/docs/CommandLine.rst
+++ b/docs/CommandLine.rst
@@ -2,6 +2,9 @@
 CommandLine 2.0 Library Manual
 ==============================
 
+.. contents::
+   :local:
+
 Introduction
 ============