[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 046f240 [Test] More tests where IndVars fails to eliminate a range check
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   046f240..38778e1  master     -> origin/master
Auto packing the repository for optimum performance. You may also
run "git gc" manually. See "git help gc" for more information.
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 38778e1087b2825e91b07ce4570c70815b49dcdc.
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!