Improve payment method form

Right now the form successfully collects user's payment info and lets them know they will be charged and when they'll be charged next. It'd be a lot nicer to have a better design as well as some frequently-asked-questions and helpful information to make people feel more at ease with subscribing.

For example, LinkedIn's form handles this really nicely:

No file, test, or entry point is named in the issue; first locate the payment method form and review its current flow alongside the referenced LinkedIn example. Done means the form has a more reassuring design and includes relevant FAQs and subscription information.

Written by the indexing model from the issue text.