Description

This PR adds a legend tab to topics EE.

• The legend tab contains general information about topics EE.

Relevant Technical Choices

Testing Instructions

• Open PSAT and navigate to topics EE.
• Open the Legend tab, the tab should contain basic information about topics.
• Switch between tabs should not affect the EE, no distorted figures should be present.

Additional Information:

Screenshot/Screencast

Checklist

• I have thoroughly tested this code to the best of my abilities.
• I have reviewed the code myself before requesting a review.
• This code is covered by unit tests to verify that it works as intended.
• The QA of this PR is done by a member of the QA team (to be checked by QA).

Partially addresses #856