[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 57a26bb [InstCombine] Fix typo in comment (NFC)
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   57a26bb..3e69871  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 3e69871ab5a66fb55913a2a2f5e7f5b42899a4c9.
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!