New partial updates logging APIs: Docs

[teh-cmc]

We need a documentation page dedicated to all things partial update.

It should include snippets.

Notes:

• Mention that partial updates still work at the component-batch layer like everything else, not the instance layer.
  • This is about updating individual batches of a single archetype.
• Mention how this respects tagging? (we don't have any doc about tagging yet though, and this is a very involved subject...)