docs: add instance lifecycles documentation

Description

This MR adds a documentation for the instance lifecycles we have at the time of writing.

Supporting information

The graph is created with mermaid, so we can extend it anytime.

Testing instructions

Steps to test the changes:

1. Proofread the changes and validate the graph is correct.

Dependencies

N/A

Screenshots

Checklist

If any of the items below is not applicable, do not remove them, but put a check in it.

• All providers include the new feature/change
• All affected providers can provision new clusters
• Unit tests are added/updated
• Documentation is added/updated
• The TOOLS_CONTAINER_IMAGE_VERSION in ci_vars.yml is updated
• The grove-template repository is updated

Additional context

N/A