[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 2ccbf3d [SDAG] fold x * 0.0 at node creation time
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   2ccbf3d..e3475f5  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to e3475f5b91c8dc3142b90b2bb4a1884d6e8d8c2c.
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!