Fix comments, remove flex-grow and unused margin
Fix comments, remove flex-grow and unused margin

Based on comments on the associated pull request,
(and my realisation that I was using flexbox
wrong):

https://github.com/alphagov/notifications-admin/pull/4171

Removal of flex-grow

I added `flex-grow: 1` to make the description and
status flex items grow to fill the container, at
least until they hit their `max-width`. They
already have `width: 100%` which achieves the same
thing so this removes it.

alphagov/notifications-admin,alphagov/notifications-admin,alphagov/notifications-admin,alphagov/notifications-admin