[translations] Add GTFS features to the glossary

[isabelle-dr]

In the next release, gtfs.org will include GTFS features, which are new GTFS concepts that represent the list of functionalities that can be modeled using GTFS.
The glossaries need to be updated with a translation for them in every language we have available.

GTFS Feature group	GTFS Feature
Base	Agency
Base	Stops
Base	Routes
Base	Service dates
Base	Trips
Base	Stop Times
Base add-ons	Route Colors
Base add-ons	Bike Allowed
Base add-ons	Headsigns
Base add-ons	Shapes
Base add-ons	Location types
Base add-ons	Feed Information
Base add-ons	Attributions
Base add-ons	Transfers
Base add-ons	Frequencies
Base add-ons	Translations
Accessibility	Stop Wheelchair accessibility
Accessibility	Trip Wheelchair accessibility
Accessibility	Text-to-speech
Fares	Fare Products
Fares	Fare Media
Fares	Route-Based Fares
Fares	Time-Based Fares
Fares	Zone-Based Fares
Fares	Fare Transfers
Fares	Fares V1
Pathways	Pathways connections
Pathways	Pathways details
Pathways	Levels
Pathways	In-station traversal time
Pathways	Pathways signs
Flexible Services	Continuous Stops
Flexible Services	Booking rules
Flexible Services	Predefined routes with deviations
Flexible Services	On-demand services with Zones
Flexible Services	On-demand services with Fixed Stops