[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 306571c [ORC][examples] Temporarily remove LLJITWithChildProcess until ORC TPC lands
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   306571c..8931c3d  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 8931c3d682763e6129f8d05ebe4e3b8dcc3e08e2.
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!