[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 88f2fe5 Raland D87318 [LLD][PowerPC] Add support for R_PPC64_GOT_TLSGD_PCREL34 used in TLS General Dynamic
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   88f2fe5..1c1a810  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 1c1a8105580784c96212db1afc097a844740bc69.
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!