[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 4fe5615 [ARM][MVE] Enable tail predication for loops containing MVE gather/scatters
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   4fe5615..0e70a12  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 0e70a127a942ee28c50391ff1198b0928c7d1597.
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!