bug#3300: 23.0.93; doc string of resize-mini-windows

> > "means let mini-windows grow only, until their display 
> > becomes empty, at which point the windows go back to
> > their normal size."
>  
> > That is not what happens.
> > M-x hhhhhhhhhhhhh C-q C-j kkkkkkkkkkkkk C-q C-j mmmmmmmmmmmmmmmm
> > Then use backspace or whatever, to empty the minibuffer.
> 
> IIUC your "empty minibuffer" is not the same as "their display becomes
> empty".  E.g. your minibuffer still has a prompt and a cursor, so its
> display is not empty.

If "empty" here is really referring to a minibuffer with no prompt and no
cursor, then:

1. We should make that clear. It sounds like what is really meant is the
situation where the minibuffer window is inactive. If so, please make that
explicit.

2. Perhaps the default value should not be `grow-only'.

`grow-only' keeping the grown size until the user input is empty (which was my
misinterpretation of the doc string) might be reasonable. But if there is no
input in the minibuffer, then perhaps the grown size should not, by default, be
retained.

I'd sooner see `t' as the default value. But I don't use this, so perhaps others
should be polled.

In any case, the doc string should be made clear in this regard, wrt what
`grow-only' really means.