Improve documentation, provide better examples

[jonhealy1]

What can we do to help people, especially people newer to STAC, understand how this project works? Having better documentation would definitely help. Something like this would be an improvement: stac-fastapi docs. We have a Postman collection in the examples folder but this could definitely be improved. Maybe a Jupyter notebook to help Users walk through common scenarios step by step? Also, we have a data loader script that loads example data but this could be converted into a CLI tool that helps Users ingest their own data. Any thoughts?

[jonhealy1]

We now have a online documentation page! https://stac-utils.github.io/stac-fastapi-elasticsearch-opensearch/