[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at c11c20f [NFC][Regalloc] VirtRegAuxInfo::Hint does not need to be a field
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   c11c20f..d8f58bf  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to d8f58bf53a98574ef14568fd830edac5d1fb37f3.
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!