Document built-in space views

[nikolausWest]

Add documentation describing what space views exist and what they do.

We currently only document archetypes from the perspective of the SDK which is only half the story.

Here are a couple docs queries that I would expect to include a result pointing to a space view page:

[Wumpf]

There's a very brief mention of the kind of space views here https://www.rerun.io/docs/reference/viewer/viewport but we have to overhaul that and expand it as part of upcoming blueprint documentation

Related to:

• Generate documentation for blueprint archetypes & components #5317