[FEATURE] Document forms in the quickstart

[pydanny]

Is your feature request related to a problem? Please describe.

The quickstart should document basic forms usage

Describe the solution you'd like

Provide 1-2 clear scenarios with simple code examples on how to execute this.

Similar implementations

See the rest of examples in the quickstart.

Problem solved

Make it easier for new users to understand how to use forms.

Confirmation Please confirm the following:

• [x] I have checked the existing issues and pull requests to ensure this feature hasn't been requested before.
• [x] I have read the project's documentation to ensure this feature doesn't already exist.