Update version numbers to v3.1-RC in the spec (#639)

* Update version numbers to v3.1-RC in the spec
* Update 'added in v3.1-RC' for the new fields
* Add v3.1-RC to README

Update current version to v3.0 (#625)

* Withdraw PR #546 Floating Interval in price

* Withdraw PR #457 Reservation Price

* Remove -RC and -RC2 from the spec

* Update current version number in spec

* Fix earlier version URLs

* Update current version in README to v3.0

* Set version history URL to Release Notes

Makes vehicle capacity at stations consistent between station_informa…

…tion and status (#547)

* makes vehicle capacity at stations consistent

Modify examples to say v3.0-RC (#502)

change examples from v3.0 -> v3.0-RC

* #329 - Add vehicle drop off restrictions

* #330 - Adding vehicle icons & brand information
* #331 - Reserve time for vehicle types and pricing plans
* #335 - Add pricing plans to vehicle types
* #336 - Add fields for terms and privacy policy
* #340 - Add field to designate stations that support vehicle charging
* #349 - Add optional station_parking rule to geofencing_zones.json
* #350 - Carsharing extension
* #370 - ​​Extending vehicle_types.json
* #386 - Versioning and Long Term Support
* #400 - Changes to return_types field

* #252 - Extend system_pricing_plans.json

* #136 - Add vehicle type definitions

* #219 - Add geofencing, virtual station, and dockless support
* #261 - Aggregate available vehicle_types at a station

* #25 - Add deep links for iOS, Android, and web apps

* #181 - Add feed_contact_email field to system_information.json
* #188 - GBFS documentation versioning and and feed conformance (adds gbfs_versions.json)

fixes to v2.3-RC2

makes default_pricing_plan_id optional to be non-breaking, corrects errors in code examples, labels new enums

MINOR release - backwards compatible with v2.0 , v2.1 and v2.2.

New Features: