chore: add lab for working with pseudo classes

[jdwilkin4]

We need a lab for campers to do after this workshop here

#569

Acceptance criteria

• create a new folder of the project in the frontend-cert/css-projects directory
• add your completed project in an index.html, styles.css file in that new folder
• create a markdown file for your proposed user stories. You should call it user-stories.md and place it in your new project folder