[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 64104db [gn build] Port ebf496d8055
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   64104db..018f693  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 018f6936dbcee63e0a1ffd3777e854150b8cf957.
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!