[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 11bb7c2 [MC] Set sh_link to 0 if the associated symbol is undefined
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   11bb7c2..8c39e70  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 8c39e70679e93da3af9f881d314940c570d5d822.
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!