Resolve "Bug: Item has faulty (or at least unclear) endpoint definition"

Bug fix

Summary

Clarifies the endpoints for items in the following way:

• https://{server}{/prefix}/{collection}/{manifest}/{item}/{revision}/item.json for getting a certain revision of an item
• https://{server}{/prefix}/{collection}/{manifest}/{item}/latest/item.json for getting the latest revision of an item

Furthermore, the term document has been altered to manifest for clarity in the endpoint description.

Related Tickets

Closes

Closes #8 (closed), closes #9 (closed)

Changelog

• I added a statement to the CHANGELOG.

/cc Mathias Göbel, Frank Schneider, Michelle Weidling