Improve information contacts for GDPRDisclaimer about geotrek-rando-v3

[dtrucs]

By adding a property to the settings such as:

GDPRDisclaimer: {
  organisms: string[],
  email: string[]
}

And specify in the documentation that if this prop is not provided, the application will retrieve the information from the contact's footer.

[babastienne]

The problem is not when we try to use other name or contact, but whenever we try to add some text in bold (<b>) or a link (<a>) it is override with informations from the footer, which can be annoying and mostly is not documented anywhere so it seems like a bug to someone who don't look at the code.