Set minimum table cell width to 6rem

Description

The table in the quick actions doc has too narrow "Issue" and "Epic" columns and the Yes/No + their SVGs are rendered in two lines.

This MR sets the minimum table cell width to 90px so they appear together. If using absolute values is bad practice, 6em worked for me too.

Tested in Chrome and Firefox on my Linux OS (Manjaro).

Before and after screenshots

Before	After (90px)