feat: add Forms section

[afontcu]

I believe handling forms is one of the main usages of Vue, and one of the common target of tests.

Thus, I would

• showcase how to perform simple, basic assertions and interactions on a form.
• showcase how to use VTU + vuelidate (once they update to Vue 3)
• showcase how to use VTU + vee-validate (once they update to Vue 3)

[lmiller1990]

Another thing that comes to mind is forms built with Vuetify/BootstrapVue.

[afontcu]

Yes! I'm not sure if it would be better to have some sort of "Popular third-party libraries" and showcase some examples, or if we should group them depending on their usage:

forms
  - basic forms
  - with vuelidate
  - with vee-validate
  - with vuetify
  - with bootstrapvue

modals
  - basic
  - with vuetify
  - with bootstrapvue

or

third-party libraries
  - vuetify
    - forms
    - modals
    ...
  - bootstrapvue
    - forms
    - modals
    ...

[lmiller1990]

I think we can start with regular HTML forms - I'm guessing it will be some time before the third party libs have upgraded.

[afontcu]

Closed in #23