Update readme.md

Typo

Author: 0crap

readme.md

@@ -122,7 +122,7 @@ Before creating new issues please check to see if there is an existing one, sear
 
 Please refer to the development section in the [docs/development](https://github.com/iNavFlight/inav/tree/master/docs/development) folder.
 
-Nightly builds are avaialble for testing on the following links:
+Nightly builds are available for testing on the following links:
 
 https://github.com/iNavFlight/inav-nightly/releases