[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at b475eca [llvm-readobj/elf] - Merge mips-got-overlapped.test to mips-got.test and refine testing.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   b475eca..9b32ef9  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 9b32ef9413be2f18ad98f24454854b438b5d9214.
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!