docs: onboarding

[alee]

set up onboarding docs that describe how to set up a local dev environment for skope-api and skopeui

should cover the architecture as well as how to load data into geoserver and to be used by the skope-api backend via https://github.com/openskope/skope-data-loader

[alee]

also cover geospatial file formats, python libraries for accessing them

• rasterio https://rasterio.readthedocs.io/en/stable/
• geojson_pydantic https://github.com/developmentseed/geojson-pydantic
• shapely https://shapely.readthedocs.io/en/stable/manual.html

[alee]

also cover fastapi + anyio: https://fastapi.tiangolo.com/async/