[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 159f9a6 [Test] Add test showing some simple cases that IndVarSimplify does not cover
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   159f9a6..9f18f3c  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 9f18f3c858d5ff8154701a50c2be6f7b19667a1d.
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!