[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at eda450b [mlir][SymbolTable] Use Identifier instead of StringRef when looking up symbol name attributes
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   eda450b..e5766f2  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to e5766f25c62c185632e3a75bf45b313eadab774b.
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!