API key required for Holiday API

README.md

@@ -95,7 +95,7 @@ For information on contributing to this project, please see the [contributing gu
 | API | Description | Auth | HTTPS | Link |
 |---|---|---|---|---|
 | Church Calendar | Catholic liturgical calendar | No | No | [Go!](http://calapi.inadiutorium.cz/) |
-| Holidays | Free API for obtaining information about holidays. | No | No | [Go!](http://holidayapi.com/) |
+| Holidays | Free API for obtaining information about holidays. | `key` string | No | [Go!](http://holidayapi.com/) |
 | LectServe | Protestant liturgical calendar | No | No | [Go!](http://www.lectserve.com) |
 | Non-Working Days | Database of ICS files for non working days | No | Yes | [Go!](https://github.com/gadael/icsdb) |