[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 2ad5611 [gn build] (manually) port 10b1b4a23
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   2ad5611..6b89489  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 6b8948922c59c9f786996387b41d8e29ed3e7a8a.
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!