[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at f3e667b [gn build] Port 418121c30a8
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   f3e667b..411eb87  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 411eb87c7962ec817ab6bf7aa3c737a3159d2d4e.
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!