[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at e63cc81 [SVE] Lower fixed length vector integer shifts.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   e63cc81..da0592e  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to da0592e4c8df95efad4e42d63646f8a5336a7edc.
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!