RE: Add hook to end of `custom-create-buffer-internal'

[Drew Adams]

    I general, we want to do the following:
    - display the buffer in a window, so we know the properties of
      the window.
    - fill the buffer with whatever text needs to be there,
      potentially using info about the window such as its width.
    - re-adjust the window to the content of the buffer.

And then run the hook - that is what I'm asking for, at least. A user's hook
could do anything, and it is good for it to run after the buffer is
completely set up.