[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 666ef0db [AMDGPU] Add gfx602, gfx705, gfx805 targets
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   666ef0db..f2e08c6 master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to f2e08c688e6c3223d14c4817c5ce0b55c03a8d1b.
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!