[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at f702a6f Thread safety analysis: Improve documentation for ASSERT_CAPABILITY
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   f702a6f..6d374cf  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 6d374cf78c8a80a0bbfc7ce9bc80b3f183f44c80.
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!