CMake: Added notes pointing to the LLVM CMake documentation.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68429 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 95f36a2..6af569b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,3 +1,5 @@
+# See docs/CMake.html for instructions about how to build LLVM with CMake.
+
 project(LLVM)
 cmake_minimum_required(VERSION 2.6.1)