[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at b8c2d60 [WebAssembly] Improved LLD error messages in case of mixed wasm32/wasm64 object files
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   b8c2d60..30e7df0  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 30e7df0d58542ad35d517eace70a4cea40e6fa7a.
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!