Usage examples

It would be good to get at least some parts of the [current asdf tutorials](https://github.com/asdf-format/tutorials/tree/main/notebooks) working here. Currently fails on the [first tutorial](https://github.com/asdf-format/tutorials/blob/main/notebooks/Anatomy_of_an_ASDF_file.ipynb) due to custom YAML tags not currently being supported, in particular the `!core/extension_metadata-1.0.0` tag