[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at a27398a [PowerPC] Update MemorySanitizer test to cater for number of CPUs > 1024
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   a27398a..f09ccf8  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to f09ccf89fbee976bcca77b374f69987c2e96e1ce.
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!