[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 28ccc52 [X86] Add feature for Fast Short REP MOV (FSRM) for Icelake or newer.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   28ccc52..dac0b1d  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to dac0b1d33088429cdaf795e81e8576288460c67d.
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!