Added instructions for obtaining clang-tools-extra to the Getting Started page.

llvm-svn: 316468
diff --git a/llvm/docs/GettingStarted.rst b/llvm/docs/GettingStarted.rst
index 529bc6d..a90a4b0 100644
--- a/llvm/docs/GettingStarted.rst
+++ b/llvm/docs/GettingStarted.rst
@@ -52,6 +52,12 @@
    * ``cd llvm/tools``
    * ``svn co http://llvm.org/svn/llvm-project/cfe/trunk clang``
 
+#. Checkout Extra Clang Tools **[Optional]**:
+
+   * ``cd where-you-want-llvm-to-live``
+   * ``cd llvm/tools/clang/tools``
+   * ``svn co http://llvm.org/svn/llvm-project/clang-tools-extra/trunk extra``
+   
 #. Checkout LLD linker **[Optional]**:
 
    * ``cd where-you-want-llvm-to-live``