[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at b0750e2 Fix rollback of first block erasure in a region.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   b0750e2..a91e967  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to a91e96702a3b8ef19afc5b7d2e51ce6b6a7fded9.
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!