docs: add UI designs for proposed features

[kineticdesigner42]

Overview

Hello 👋

Following @ChakshuGautam's comment, I am making this pull request, which adds a design.md file with individual UI designs for the following features -

• Expiry status
• Expiry editor
• Campaign folders

Please do give any feedback or comments on the designs. Thank you :D

Related Issues

• This PR is related to #52

[Nazi-pikachu]

@kineticdesigner42 Thank you for the PR They proposed UI features looks pretty solid.

[ChakshuGautam]

LGTM!!! Thanks @kineticdesigner42 for this. Let's discuss the design on tickets. Will create 4 tickets for the Figma design.