[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 81733fd [X86] Pre-commit the test-shrink.ll changes from D86578.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   81733fd..342fea3  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 342fea366f907e09eb12b12cfdeba7e9a056c2a3.
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!