[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 43465a4 [LegalizeTypes][X86] Add ROTL/ROTR to WidenVectorResult.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   43465a4..0e6c9a6  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 0e6c9a6e7940a2f8ee624358d828acffdb9ccca5.
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!