[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 6313f55 [llvm-readobj] [ARMWinEH] Fix printing of exception handlers with packed epilogues
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   6313f55..b81c57d  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to b81c57d646e49c15de1b6e2938b8689b7854a02b.
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!