New documentation for js-dataverse v2

[GPortas]

What this PR does / why we need it:

Adds updated and structured documentation to the package, for its next release to version 2.

The docs include a section dedicated to use cases, which includes a description and example calls for each of the use cases available in the package.

Which issue(s) this PR closes:

• Closes Create new documentation for version 2.0.0 #113

Related Dataverse PRs:

• None

Special notes for your reviewer:

• We need to add docs for Adds create dataset use case #114
• We need to add docs for 117- Create use case to get the file citation #125

Suggestions on how to test this:

• Instead of looking at file diffs, I suggest opening the GitHub repository branch for a better view of the markdowns and for link testing: https://github.com/IQSS/dataverse-client-javascript/tree/113-documentation-v2

[MellyGray]

@GPortas There's an integration test failing. I think is some kind of race condition, where sometimes there are more dataset locks occurring than those expected by test's assertion

[MellyGray]

LGTM! For future iterations, I would suggest adding a "Go Back to Index" button on all the documentation pages, as it can be frustrating trying to navigate back to the index