[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 7e32797 [llvm-readobj] - Don't call `unwrapOrErr` in `findSectionByName`.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   7e32797..d100747  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to d1007478f19d3ff19a2ecd5ecb04b467933041e6.
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!