Update spacing info
From: gitlab-org/gitlab-design#162 (comment 82941504)
"the 'standard' is
8px
margin for related elements and16px
margin for unrelated elements. I don't believe this has ever been written down, but these measures seem to be common in the design system. The app is still mostly using multiples of10px
, so these measurements are not enforced in production."
Let's get the spacing guidelines updated with this information.