[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at ad0e764 [libc][obvious] Fix fdim[f|l] signatures in stdc spec.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   ad0e764..8c1e3cb  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 8c1e3cbebfe9ff14829a279b9d229d4fc3f190b1.
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!