[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 5053eab Revert "[PowerPC] Extend folding RLWINM + RLWINM to post-RA."
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   5053eab..d9a4f93  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to d9a4f936d05c1e8740f5f73da1b149c36d25d02c.
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!