Card documentation

This merge request intends to start discussing the documentation for the Card component.

#287

.gitlab/merge_request_templates/New page.md

-## Description
-
-(Add a short description about what this new page covers)
-
-## References
-
-(Link related Design System or GitLab Design issues)
-
-## Checklist
-
-* [ ] Page link with corresponding status added to `getting-started/status.vue`
-* [ ] Check if cross-reference to this page from other pages might be relevant or helpful
-<!-- For pages outside components only (NOT pages/components/) -->
-* [ ] Page link added to `layout/default.vue`
-<!-- For component pages only (pages/components/) -->
-* [ ] Depending on type of the page, content should follow the documentation template
-  * [Component page template](https://gitlab.com/gitlab-org/gitlab-services/design.gitlab.com/blob/master/pages/components/template.vue)