Explain keywords inline

[Reinmar]

Stuff like "attributes", "startOffset", etc could link to API docs. Some might also be worth describing inline so the user will not need to go somewhere else.

I don't want to clutter the UI with unnecessary stuff, so perhaps this is not the best idea, but one way to do that could be by adding a hoverable/clickable "?" next to those items and describe those things in those tooltips.