[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 5f4abb7 [Hexagon] Replace incorrect pattern for vpackl HWI32 -> HVi8
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   5f4abb7..2ce1a69  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 2ce1a697f037469e737db1ad41dfa14ec653ec53.
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!