[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at a012bc4 [analyzer][StdLibraryFunctionsChecker] Elaborate the summary of fread and fwrite
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   a012bc4..01f5fcd  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 01f5fcd8290349265e6039ad9089b086ea783f00.
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!