Missing config tables and docstrings for some scripts

[davide-f]

Describe the feature you'd like to see

The configtables for several pypsa-earth-related scripts are missing. A non-exhaustive list is the following:

• [ ] download_osm_data docstring&configtables
• [ ] clean_osm_data docstring&configtables
• [ ] build_shapes docstring&configtables
• [ ] build_osm_network docstring&configtables
• [ ] base_network only configtables
• [ ] "load_options"; need for creating the build_demand and move the option as well accordingly

[GbotemiB]

@davide-f I am reviving this issue as it is useful for the documentation challenge.

[GbotemiB]

There a few more things that can be fixed or updated.

• [ ] update config tables to include -sector coupled parameters
• [ ] Include docstrings in sector coupled scripts as this is useful for API reference section in the documentation.