[docs] Clarify ENABLE_MODULES uses Clang Header Modules.

Suggested post-commit by @dblaikie, thanks!

diff --git a/llvm/docs/CMake.rst b/llvm/docs/CMake.rst
index 212a8d1..c45f854 100644 (file)
--- a/llvm/docs/CMake.rst
+++ b/llvm/docs/CMake.rst
@@ -306,8 +306,9 @@ LLVM-specific variables
   scenario where a manual override may be desirable is when using Visual Studio
   2017's CMake integration, which would not be detected as an IDE otherwise.
 
-**LLVM_ENABLE_MODULES**
-  Compile with C++ modules enabled.
+**LLVM_ENABLE_MODULES**:BOOL
+  Compile with `Clang Header Modules
+  <https://clang.llvm.org/docs/Modules.html>`_.
 
 **LLVM_ENABLE_PIC**:BOOL
   Add the ``-fPIC`` flag to the compiler command-line, if the compiler supports