[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at e202236 [IR] Add IRBuilderBase::CreateVectorSplat(ElementCount EC) variant
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   e202236..e7a8ee0  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to e7a8ee00e6c3b20fc04792db1acf9d5324a1b7bb.
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!