[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at b9f2b3b [AArch64][GlobalISel] Scalarize <2 x s64> G_MUL since we don't have native support for it.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   b9f2b3b..ca1ce39  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to ca1ce397acc39f348f4018e446c84a5746fd5e1e.
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!