[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at d266fd9 [IndVars] Remove exiting conditions that are trivially true/false
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   d266fd9..4fc69ab  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 4fc69ab002382675d84f611f22599cb3cb4a0787.
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!