ability to set the max size of the completion menu

[crypticC0der]

Is your feature request related to a problem? Please describe.
the completion menu whe the number of options is large can take up the entire nvim window and it can hinder usability

Describe the solution you'd like
ideally there would be an option to set the max line height of the menu

Describe alternatives you've considered
ive looked all around and cant seem to find it implemented anywhere

[Shougo]

set pumheight=20