Improve documentation

[mficzel]

• How to add Add DateTemplate to additional fields
• How to add default fields and validators that are not content (Automatic Submit Button, Automatic Honeypot)

[mficzel]

Note: This is what currently has to be done for automatically adding fields ... i think it should be improved first before documenting this further.

prototype(Vendor.Site:Content.ContactForm) < prototype(Neos.Fusion:Component) {

    renderer = Sitegeist.PaperTiger:Form
    
    prototype(Sitegeist.PaperTiger:FieldCollection.Renderer) {
        @process.addField = Neos.Fusion:Join {
            value = ${value}
            extra = Sitegeist.PaperTiger:Field.Text.SingleLine {
                name = "extra"
            }
        }
    }

    prototype(Sitegeist.PaperTiger:FieldCollection.Schema) {
        renderer.schemaMap.@process.addSchema = ${Array.set(value, 'extra', Form.Schema.string().required )}
    }
}