Document platform formats and export formats

There's several platforms and export formats that are not documented. It would be great to understand what is legacy and what is the correct choice if one uses the format today i.e. how to make a selection
```
--export-format EXPORT_FORMAT
Export json with non crytic-compile format (default None. Accepted: (standard, crytic-compile, solc, truffle, archive)
```
It's also unclear what is the difference between `solc-json` and `standard` for the platforms since it sounds like they could both use the solc standard json format

Start with the CLI help entry for --export-format and the platform and export-format definitions referenced by the issue. Trace the accepted values, including solc-json and standard, to determine which are legacy and which should be selected today. Done means the documentation explains each platform and export format, their differences, and how to choose among them.

Written by the indexing model from the issue text.