[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 99a971c [X86][SSE] Start shuffle combining from ANY_EXTEND_VECTOR_INREG on SSE targets
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   99a971c..42a9f6c  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 42a9f6c554e378f1c010375eca30f04296aa0052.
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!