[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 6b89489 [AMDGPU][MC] Added support of SP3 syntax for MTBUF format modifier
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   6b89489..c332a98  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to c332a984aefc6f8a6b44fd3687a5bbce3f8f035c.
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!