Tutorial improvement

[martinkarbon]

• Denodo:
  * move content away from the slides? The slides are deprecated
  *clarify "Selection" and add screenshot to the presentation, ore remove it?
  *clarify "Unfold properties"
• Check that the prefix ex is preserved in the mapping files
• Change titles of the sidebar
• Add Mapping of Assistant Professor (university-no-pk.obda, university-no-fk.obda, university-manual-ssn.obda, university-canonical.obda )
• Dremio - mapping assertions: missing ex prefix? (not sure)
• Mapping/URI-templates: check the mapping-target-syntax(if they are correct)
• Migrate the last commits in the ontop-tutorial (Dremio)

[Muffexx]

One additional needed improvement:

• Dremio - add download link for uni2.json file