Fix 'fit-frame-to-buffer' (Bug#56102)

Fix 'fit-frame-to-buffer' (Bug#56102)

* lisp/window.el (fit-frame-to-buffer-sizes): Fix doc-string.
Give calls to 'max' a second argument so they do something
useful.  If ONLY equals 'vertically', call
'window-text-pixel-size' with X-LIMIT nil (Bug#56102).  For
minimum sizes of the window to fit, use 'window-safe-min-size' by
default.
* doc/lispref/windows.texi (Resizing Windows): Fix descriptions of
'fit-frame-to-buffer' and 'fit-frame-to-buffer-sizes'.