[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 8954fd4 [libcxx] Fix regression where `ninja all` doesn't copy libcxx headers
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   8954fd4..895ae48  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 895ae487a2824916d3f8b37afbdd9f26b2cb5d11.
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!