Updated APIs list with ADS-B aircraft API

Created a new category for the ADS-B real-time aircraft flight status information API from ADS-B Exchange.

README.md

@@ -14,6 +14,7 @@ Please note a passing build status indicates all listed APIs are available since
 * [Anime](#anime)
 * [Anti-Malware](#anti-malware)
 * [Art & Design](#art--design)
+* [Aviation](#aviation)
 * [Books](#books)
 * [Business](#business)
 * [Calendar](#calendar)
@@ -83,6 +84,11 @@ API | Description | Auth | HTTPS | Link |
 | Noun Project | Icons | `OAuth` | No | [Go!](http://api.thenounproject.com/index.html) |
 | Rijksmuseum| Art | `apiKey` | Yes | [Go!](https://www.rijksmuseum.nl/en/api) |
 
+### Aviation
+API | Description | Auth | HTTPS | Link |
+|---|---|---|---|---|
+| ADS-B Exchange | Access real-time and historical data of any and all airbone aircraft. | No | Yes | [Go!](https://www.adsbexchange.com/data/) |
+
 ### Books
 API | Description | Auth | HTTPS | Link |
 |---|---|---|---|---|