[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 2a75e95 Revert "[InferAttrs] Add argmemonly attribute to string libcalls"
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   2a75e95..9d2b830  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 9d2b8300b768715bb3e0e151de37136f29b29590.
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!