[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 4b38ceb [X86] Remove MWAITX_SAVE_EBX pseudo instruction. Always save/restore the full %rbx register even in gnux32.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   4b38ceb..9756a402 master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 9756a402f297d0030689aaade3651785b7496649.
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!