text: Title: Document and communicate dropped support for win32
  Body: The 0.57.x line of Numba is the last to support `win32` -- that is the Windows 32 bit platform as per the LLVM target identifier.
  
  This means, that for 0.58 this drop in supported platforms must be communicated, that is to say:
  
  * [ ] Find all occurrences of and remove win32 advert and descriptions in the documentation
  * [ ] Remove any win32 specific hacks from ci config and recipes
  * [ ] Mention this in the release notes