Split 'Getting Started' docs page into sub-pages

[pederhan]

The current "getting started" page is currently too crammed with information and is difficult to navigate.

It's better if each topic is given its own page, e.g.:

• Authenticating
  • Current contents are sufficient, just needs its own page
• Fetching (or something similar)
  • Single resource
  • Multiple resources: Explain sort, query, page, page_size, etc.
• Updating
  • In this section we explain that we primarily pass Pydantic models as arguments, but that we can also pass dicts
  • Explain that dicts are not subjected to validation, so users will receive HTTP errors (as opposed ValidationError) if they try to pass in invalid data. They will also get no help from their IDE.
• Deleting
  • Deletion is mostly done via IDs and rarely (if ever?) return anything, so this one is simple.
• Examples
  • Current examples might be moved here, moved to "recipes", or dropped altogether as the previous pages should have explained most things well enough.

[pederhan]

Resolved by 93c64731605afe5ef232f04a074e45a5ca9c0b57