[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 512e256c [PowerPC] Add clang options to control MMA support
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   512e256c..19311f5 master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 19311f5c3e9ada9d445e49feb7a2ae00ddaee2fa.
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!