[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at d236e1c [InstSimplify/NewGVN] Add option to control the use of undef.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   d236e1c..2a11d5d  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 2a11d5dcc97a454bfd6db0771709cd554a5ccfac.
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!