Add iRail CORS detail, improve description (#2769)

README.md

@@ -1489,7 +1489,7 @@ API | Description | Auth | HTTPS | CORS |
 | [TransitLand](https://transit.land/documentation/datastore/api-endpoints.html) | Transit Aggregation | No | Yes | Unknown |
 | [Transport for Atlanta, US](http://www.itsmarta.com/app-developer-resources.aspx) | Marta | No | No | Unknown |
 | [Transport for Auckland, New Zealand](https://api.at.govt.nz/) | Auckland Transport | No | Yes | Unknown |
-| [Transport for Belgium](https://hello.irail.be/api/) | Belgian transport API | No | Yes | Unknown |
+| [Transport for Belgium](https://api.irail.be/) | The iRail API is a third-party API for Belgian public transport by train | No | Yes | Yes |
 | [Transport for Berlin, Germany](https://github.com/derhuerst/vbb-rest/blob/3/docs/index.md) | Third-party VBB API | No | Yes | Unknown |
 | [Transport for Bordeaux, France](https://opendata.bordeaux-metropole.fr/explore/) | Bordeaux Métropole public transport and more (France) | `apiKey` | Yes | Unknown |
 | [Transport for Boston, US](https://mbta.com/developers/v3-api) | MBTA API | No | No | Unknown |