[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at e7081d1 AMDGPU: Implement waterfall loop for MIMG instructions with 256-bit SRsrc
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   e7081d1..d9ff48d  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to d9ff48d03817f83d4059b610a776c797308de2e5.
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!