Add encoding examples of Jelly in an appendix

[Ostrzyciel]

Same motivation as with #34

We could have an appendix (probably on a separate page) describing example encodings of terms and streams of RDF, like here: https://openengiadina.codeberg.page/rdf-cbor/#appendix-A

Note that the Jelly spec already has examples in it. So, probably the examples would have to be moved to the appendix. Instead, we could add well-highlighted links/clickable buttons to the relevant examples in the spec.

Not sure if this is the right approach, any inputs welcome.