[www-scripts] Clang Attribute Doc Update: ERROR

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UPDATING LLVM SOURCES
HEAD is now at 57bd64f Support addrspacecast initializers with isNoopAddrSpaceCast
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   57bd64f..7ad6ea5  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 7ad6ea520fe49e9320bd15a4daf88e36259efedc.
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!