Add a TOC to the C++ tutorial.

RELNOTES: None.
PiperOrigin-RevId: 164283165

site/docs/tutorial/cpp.md

diff --git a/site/docs/tutorial/cpp.md b/site/docs/tutorial/cpp.md
index 95898e3..36de924 100644
--- a/site/docs/tutorial/cpp.md
+++ b/site/docs/tutorial/cpp.md
@@ -25,6 +25,22 @@
 *  Control target visibility across packages
 *  Reference targets through labels
 
+## Contents
+
+*  [Before you begin](#before-you-begin)
+   *  [Install Bazel](#install-bazel)
+   *  [Get the sample project](#get-the-sample-project)
+*  [Build with Bazel](#build-with-bazel)
+   *  [Set up the workspace](#set-up-the-workspace)
+   *  [Understand the BUILD file](#understand-the-build-file)
+   *  [Build the project](#build-the-project)
+   *  [Review the dependency graph](#review-the-dependency-graph)
+*  [Refine your Bazel build](#refine-your-bazel-build)
+   *  [Specify multiple build targets](#specify-multiple-build-targets)
+   *  [Use multiple packages](#use-multiple-packages)
+*  [Use labels to reference targets](#use-labels-to-reference-targets)
+*  [Further reading](#further-reading)
+
 ## Before you begin
 
 To prepare for the tutorial, first [Install Bazel](../install.md) if