[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 1c19900 [PowerPC] Add RUN line for powerpc 32-bit. NFC.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   1c19900..137da82  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 137da82b868266b0ef855ccfeb3795dbf2e2b50f.
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!