[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at b358dad [ELF] Re-initialize InputFile::isInGroup so that elf::link can be called more than once
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   b358dad..416a6a8  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 416a6a85b14883149a1eb48c9705dad097704d3b.
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!