[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 1d54e75 [GlobalISel] Fix multiply with overflow intrinsics legalization generating invalid MIR.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   1d54e75..6f01c53  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 6f01c53f26af7fb0393464079ec5e839a497d4da.
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!