[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 0c005be [X86][SSE] getV4X86ShuffleImm8 - canonicalize broadcast masks
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   0c005be..aec38c6  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to aec38c619dfa1c41b6b0f6c52a31d221ac108b6b.
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!