Add Rich Snippets to checking deployed markup tutorial

[AlasdairGray]

In PR363 @ljgarcia suggested

I suggest to add an example with https://search.google.com/test/rich-results as https://search.google.com/structured-data/testing-tool is supposed to be deprecated and replaced by the former. This does not have to be done as part of this PR so approving now with the current content.

[AlasdairGray]

I'm not that keen to include the rich snippets tool. It only works for a very limited number of types within Schema.org and doesn't provide a useful interface for other types.

I think we are better to stick with the new Schema Markup Validation Tool, and remove both the others.

[ljgarcia]

So, it would be Schema Markup Validation and BMUSE, right? Sounds good to me

[AlasdairGray]

After the validation meeting we should revamp this tutorial to include the different tools that we have in the community:

• Schema.org Markup Validator
• FAIR Checker
• Manchester Validator
• Validata
• Data Discovery Engine

[ljgarcia]

We need volunteers to work on updating this tutorial with all the listed options. Maybe someone in your group @AlasdairGray or maybe @albangaignard ? You both have worked on the data validation