[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 3af4039 [ELF][test] Add another -triple=x86_64 to linkorder-mixed.s
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   3af4039..3a538de  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 3a538de653607b7602a870d63b13dd51638c1424.
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!