Show that more elements are available on scroll

[simjnd]

Is your feature request related to a problem? Please describe.
Use gum table < test.csv --height 3 when test.csv has 10 rows. It will display a table that has 3 rows and no way of knowing if you've reached the bottom of the table or if there is more available by "scrolling".

Describe the solution you'd like
When there are more elements available, show an indication (e.g. add a row with dark gray ... showing content has been clipped from the viewport)

Describe alternatives you've considered
N/A

Additional context

How many items are there?

Turns out there are a lot!

[olivertzeng]

I like the idea!