Write documentation

[insin]

[citelao]

Some things that can only be found in the source code atm:

Optional Properties

• component: what HTML component to render as the enclosing <form>. Defaults to form.
• dataKey: what key to place extracted form data in, i.e. location.state[dataKey]. Defaults to body.
• extractFormData: function to use to extract form data into JS object. Receives event.target. Defaults to get-form-data.
• methodKey: what key to place extracted form submission method in, i.e. location.state[methodKey]. Defaults to method.
• onSubmit: function to run on form submission. Receives (event, formData) where event is the SyntheticEvent and formData is the extracted form data (see extractFormData). Defaults to null.