[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at f76adc2 [docs] Add an initial (non-exhaustive) list of intrinsics that can be used in constant expressions
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   f76adc2..b014cc0  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to b014cc0f655da5094302c326d6d0576fdb652e58.
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!