Documentation for handling observatiory-specific settings

[mikkohei13]

Check how bird observatiory -specific settings are handled. E.g. pyydystiedot, peruslajit & paikat for Jurmo observatory. Then make brief documentation about this to the repository.

[aorin]

@mikkohei13 here is the doc: https://github.com/luomus/lintuasemasovellus/blob/dev/documentation/developmentInstructions/addingNewObservatory.md. Some things are hard-coded so there's a need for code changes to get the Jurmo observatory working.