[Onboarding] - Fix Create/edit checklist modals

[Aaryan1203]

Desired Changes

"We want to push people toward writing one description. An idea could be having a description text box, and then giving an option to "Add Additional Information" which can look like the bullet field we have now" - Sean

Right now the checklist modals has an option to add a description and then add multiple descriptions. As per Seans comment, what makes more sense is to just have a textbox for one description and then when you click "Add Additional Information", then you get the bullet field like it is right now

Screenshots (as needed)

No response