[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 5abf76f ADT: Add assertions to SmallVector::insert, etc., for reference invalidation
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   5abf76f..c0958b7  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to c0958b7b4c6a31b0b89462c3ee770e486d4eb535.
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!