Add synonyms to geocoding

[leonardehrenfried]

The Sheet Geocoding Synonyms declares a couple of synonyms which should used by the Geocoding. For every row, all column values of this row should be treated as synonyms.

A documentation where synonyms can be added in future should be provided. i.e. it should be documented, what needs to be done to apply new synonyms, and if this would require a complete re-import of at least photon.

[leonardehrenfried]

The original synonyms still work:

https://photon-eu.stadtnavi.eu/api?q=klinikum%20herrenberg
https://photon-eu.stadtnavi.eu/api?q=krankenhaus%20herrenberg

I will add the new ones a write a bit of documentation how they work.