add window-numbering-update to minibuffer-setup-hook

Hi!

You have this variable `window-numbering-auto-assign-0-to-minibuffer`, which does exactly what I want. However, it wasn't working for me out-of-the-box, because `window-numbering-update` wasn't called when I entered the minibuffer. So, I needed to add `window-numbering-update` to `minibuffer-setup-hook` to make it working.

Do you think that's something that had to be done in the first place or am I missing something?