[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at a461e76 [MachineScheduler] Inform pass infra of post-ra scheduler's dependencies
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   a461e76..44a11c3  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 44a11c342caa70efe9f9d07db3e66dd48f701aca.
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!