[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at ad37665 [AArch64][GlobalISel] Optimize G_PTR_ADD with a negated offset to be a G_SUB.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   ad37665..3225fcf  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 3225fcf11eb7741d4f0b7e891685d7133aae5c7b.
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!