Spanish translation falls behind English original

[egorich239]

1. gtfs-realtime.proto in Spanish and probably README.md should include disclaimer that the Spanish version is for information only, and English version takes precedence in case of differences.
2. ScheduleRelationship::REPLACEMENT should be deleted from Spanish version of gtfs-realtime.proto
3. EntitySelector fields should get some descriptions in reference.md.

[egorich239]

(2) has been addressed by #12

I can however spot other differences in the text. For example, start_time for frequency-based trips is required to be GTFS_start_time + N * headway.

[gcamp]

I would reopen this, the Spanish hasn't been updated for 7 years

[skinkie]

I guess some ChatGPT would save the day.

[isabelle-dr]

We have translations at https://github.com/MobilityData/gtfs.org that render the Spanish version of gtfs.org.
They are also out of date currently (not 7 years though), but we plan to translate the whole site in June.

I think we can delete the Spanish documentation from here.
cc @Sergiodero

[isabelle-dr]

The PR is open to removing Spanish translations from the google/transit repo, in favor of the more up-to-date translations that live on https://github.com/MobilityData/gtfs.org