[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 0b34226 Use properlyDominates in RDFLiveness when sorting on dominance.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   0b34226..2d13693  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 2d13693bfce9b6c2c706f3ea6745ab3fdfa517e1.
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!