justIN in the Data Management tutorial

[Andrew-McNab-UK]

Couple of suggestions/requests.

justIN should be consistently capitalised as "justIN" not the current mix of justIn, JustIn, JustIN, Justin etc. This also helps distinguish between the justIN system as a whole and the justin (all lowercase) command. If in doubt, just check the justIN dashboard: it's consistent there.

In "Full Justin/Rucio/Metacat Tutorial", it would be better to have the main justIN tutorial first as it covers the basics and is kept in sync with the code. Its URL is now https://dunejustin.fnal.gov/docs/tutorials.dune.md after the new production instance was set up at Fermilab. Then the Rucio/MetaCat/justIN tutorial that's in DocDB, which also needs updating for the URL changes btw. It might be worth making a note that where it disagrees with the main justIN tutorial, that is more up to date.

Thanks,
Andrew