[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at cb19e8c [libc][obvious] Include Sqrt.h in SqrtLongDoubleX86.h.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   cb19e8c..b34f116  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to b34f116856306d97aa9244a46eb1643a8ddd49a8.
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!