Prepare release 2.1

See merge request !41

Translations update from Weblate

See merge request !29

Currently translated at 100.0% (63 of 63 strings)

Translation: AlekSIS/AlekSIS-App-Resint
Translate-URL: https://translate.edugit.org/projects/aleksis/aleksis-app-resint/de/

Update translation files

See merge request !40

Bump version to 2.1 and update changelog

See merge request !39

Add docs

See merge request AlekSIS/official/AlekSIS-App-Resint!34

Port default LiveDocument.update() from Chronos

See merge request !38

Resolve "Poster group not showing up in menu"

Closes #9

See merge request !37

Resolve "Button "Create live document" does nothing"

Closes #10

See merge request !36

Merge remote-tracking branch 'origin/10-button-create-live-document-does-nothing' into 9-poster-group-not-showing-up-in-menu

Resolve ""Live documents" table has two "Actions" columns"

Closes #11

See merge request !35

Bump version of builddeps

See merge request AlekSIS/official/AlekSIS-App-Resint!33

Resolve "Open documents in a new tab (from the menu)"

Closes #4

See merge request !31