[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 0dd8782 Add a flag to control whether to propagate labels from condition values to results
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   0dd8782..1d5daed  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 1d5daed1997d2fc1fbb6fd19156518bde93d1034.
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!