[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at af4fb41 clang/StaticAnalyzer: Stop using SourceManager::getBuffer
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   af4fb41..5b346fd  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 5b346fd8c9949109802a34a8e702d31b6b3e1b70.
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!