Removing notebook 05-DIVAnd-overview.ipynb

[ctroupin]

I propose we get rid of notebook 05-DIVAnd-overview.ipynb because it doesn't really need anything on the table (part of the content could be added to the README if needed).

I know this will cause a problem in the numbering of the notebooks (no number 5 anymore), but the numbering is already a bit messed up in some of the directories).