[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 6e42cad [docs] Document LLVM_EXTERNALIZE_DEBUGINFO CMake option
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   6e42cad..88690a9  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 88690a965892e82cac05a162a9d10e2ce4e2355f.
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!