Improve formatting in click for CLI --help options

Most of the time the CLI commands use minimal formatting, but sometimes it's necessary to have lists, yaml blocks, etc

E.g. the fill-table command is quite extensive

This looks OK in sphinx:

https://incatools.github.io/ontology-access-kit/cli.html#runoak-fill-table

however in runoak fill-table --help

this shows up as:

```
- id -- the unique identifier of the element - label -- the rdfs:label of
the element - definition -- the definition of the element - mappings --
mappings for the element - ancestors -- ancestors for the element (this can
be parameterized)
```

and yaml shows as:

```
For example, my-schema.yaml:

classes: Person: attributes: id:
identifier: true name: slot_uri:
rdfs:label
```

I think the approach is here:
https://stackoverflow.com/questions/55585564/python-click-formatting-help-text

Start with the Click-based implementation of the runoak fill-table --help entry point and compare its output with the linked Sphinx page. Review the linked Click formatting approach, then verify that list and YAML examples retain readable line breaks and indentation in the CLI help output.

Written by the indexing model from the issue text.