[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 01cdab0 [gcov] Delete flush_fn_list (unused since D83149)
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   01cdab0..3e4e0fb  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 3e4e0fb2435544acadf3614d3cd7b5f0f8fdfda2.
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!