[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 29ae448 [PowerPC] Handle STRICT_FSETCC(S) in more cases
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   29ae448..7be8682  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 7be86829216698b6f4d0e083d48d7095898fc9c8.
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!