Added bottom padding to label color suggestion link

## What does this MR do?

Adds a bottom margin to label color suggestions to make sure that when wrapped there is enough whitespace between color rows.

## Are there points in the code the reviewer needs to double check?

😕 

## Why was this MR needed?

Mobile UX.

## What are the relevant issue numbers?

Closes #18857.

## Screenshots (if relevant)

![Screen_Shot_2016-06-22_at_00.31.26](/uploads/f49c7fa2b97b13e69f0dea97c5dfb319/Screen_Shot_2016-06-22_at_00.31.26.png)

## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4845