message: change heading to h1
diff: <p align="center">
  <img width="300px" src="https://user-images.githubusercontent.com/10384315/48589167-39d6b400-e8ef-11e8-9183-c69de4fe477f.png">
  -<h3 align="center">Primer Components</h3>
  +<h1 align="center">Primer Components</h1>
  <p align="center">React components for the Primer Design System</p>
  