Miscallenous doc enhancements

[eroell]

Description of feature

• [x] move from Image(filename="path/to/image.png)", width=800) to ![](path/to/image.png) or <img src="path/to/image.png" width="800"> with the correct MyST option for HTML images active if width required
• [x] Call API "API", not "Usage"
• [x] Move dedicated hub for questions in docs/tutorials/index.md from Github Discussion Section to https://scverse.zulipchat.com/#narrow/channel/465075-ehrapy

[eroell]

• [x] Title harmonization for MIMIC II IAC using tutorials
• [x] Add link to new notebook from patpy