[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 620adacf Revert "[libc++] ADL-proof <vector> by adding _VSTD:: qualification on calls."
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   620adacf..ab77fa5 master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to ab77fa515583ca906f2cb09a5f5e1ea3c48ec725.
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!