[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 3758495 [X86] Add a X86ISD::BEXTRI to distinquish the case where the control must be a constant.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   3758495..7f1b2a6  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 7f1b2a61250a4fe206aac974478471eee42d1e73.
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!