[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 02295e6 [InstCombine] matchFunnelShift - canonicalize to OR(SHL,LSHR). NFCI.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   02295e6..596a9f6  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 596a9f6b89d0d3e3f2897132ef1283941bd3607b.
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!