[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at ae1396c [ARM][BFloat16] Change types of some Arm and AArch64 bf16 intrinsics
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   ae1396c..875074c  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 875074c8a93d71b3e246da4bae983ec7524f4f28.
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!