[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 2c9dc7b Revert "[llvm-exegesis] Add option to check the hardware support for a given feature before benchmarking."
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   2c9dc7b..71dcbe1  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 71dcbe1e88b446ae7f405da1b3006b966ccc6ca6.
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!