[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 437358b [clang]Test ensuring -fembed-bitcode passed to cc1 captures pre-opt bitcode.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   437358b..b393118  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to b3931188fdc84ce2bd93a0770ddc8182d18c5010.
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!