[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 77973f8     [WebAssembly] Add support for DWARF type units
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   77973f8..735ab4b  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 735ab4be35695df9f9da7ae8b584cec28eabf1fe.
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!