[v1] Dialog docs, maximized demo breaks page if closed after minimizing

[carlfarrington]

This may just relate to the docs, rather than the QDialog component itself.

If you open up the 'maximized' demo (https://v1.quasar-framework.org/vue-components/dialog#Example--Maximized ).
Then minimize it (then it becomes a normal dialog in the middle of the window).
Then close it.
The page is no longer scrollable.

[rstoenescu]

Fix will be available on beta.3.