Explicit in the doc the current list of projects (with easy copy and paste)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@375339 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/CMake.rst b/docs/CMake.rst
index 6e385d8..3fd3ee3 100644
--- a/docs/CMake.rst
+++ b/docs/CMake.rst
@@ -374,6 +374,8 @@
   i.e. clang needs to be in parallel of llvm instead of nested in `llvm/tools`.
   This feature allows to have one build for only LLVM and another for clang+llvm
   using the same source checkout.
+  The full list is:
+  ``clang;clang-tools-extra;compiler-rt;debuginfo-tests;libc;libclc;libcxx;libcxxabi;libunwind;lld;lldb;llgo;openmp;parallel-libs;polly;pstl``
 
 **LLVM_EXTERNAL_PROJECTS**:STRING
   Semicolon-separated list of additional external projects to build as part of