FY21Q4 Foundations KR2: Audit and update buttons on Projects::BoardsController#index

"FY21-Q4 UX Department: Foundations SubTeam OKR

Objective: Ensure designers have what they need to feel confident utilizing the correct button variant, position, placement, and hierarchy.

KR2: Provide examples of correct button usage by auditing and updating the top 40 most visited pages

---

Audit and update buttons found on Projects::BoardsController#show & Projects::BoardsController#index. An example of this page can be found here: https://gitlab.com/gitlab-org/gitlab/-/boards

Follow the instructions from the parent epic and provide before and after screenshots below:

Before	After