[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at bc3615f [CMake] Use append for CMAKE_REQUIRED_* variables
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   bc3615f..6fa38de  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 6fa38de071f0993be81ea090c4a307b1d146c179.
CMake Error at CMakeLists.txt:3 (cmake_minimum_required):
  CMake 3.13.4 or higher is required.  You are running version 3.7.1


-- Configuring incomplete, errors occurred!