Fix a #include cycle in the libclang headers. "Eventually" is now.

llvm-svn: 237320
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index bffef19..5682f34 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -122,6 +122,10 @@
    objects instead of `MacroDirective` objects. This allows preserving
    full information on macros imported from modules.
 
+-  `clang-c/Index.h` no longer `#include`\s `clang-c/Documentation.h`.
+   You now need to explicitly `#include "clang-c/Documentation.h"` if
+   you use the libclang documentation API.
+
 libclang
 --------