[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 04a6ea5 [GlobalISel] Add a combine for sext_inreg(load x), c --> sextload x
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   04a6ea5..bf36e90  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to bf36e902953a4bf8ac0aae5a498445951fbc3882.
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!