[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at d938e6e [gn build] Port 412cdcf2edf
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   d938e6e..e2d4174  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to e2d4174e9c66251d1b408234b53f53d0903c0285.
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!