Update used-by.md (react-navigation#800)

* Update used-by.md

Adding Skeel to the list of great apps

* Update used-by.md

Author: Nicobas

versioned_docs/version-5.x/used-by.md

@@ -37,6 +37,7 @@ It's impossible to list every single app that uses React Navigation, but below a
 - [Rocket.Chat](https://rocket.chat/) ([Source Code](https://github.com/RocketChat/Rocket.Chat.ReactNative)) ([iOS](https://apps.apple.com/us/app/rocket-chat/id1148741252)) ([Android](https://play.google.com/store/apps/details?id=chat.rocket.android))
 - [Saffron](https://www.mysaffronapp.com/) ([iOS](https://apps.apple.com/us/app/saffron-your-digital-cookbook/id1438683531)) ([Android](https://play.google.com/store/apps/details?id=com.awad.saffron))
 - [Single Origin 2](https://singleoriginapp.com/)
+- [Skeel](https://www.skeelapp.com/) ([iOS](https://apps.apple.com/fr/app/skeel-qui-est-le-meilleur/id1292404366)) ([Android](https://play.google.com/store/apps/details?id=com.skeelofficial.reactnativeclient))
 - [Stillwhite: Wedding Dresses](https://www.stillwhite.com/) ([iOS](https://apps.apple.com/us/app/stillwhite-wedding-dresses/id1483180828)) ([Android](https://play.google.com/store/apps/details?id=com.stillwhite.app))
 - [Summer](https://www.summerapp.com/) ([iOS](https://apps.apple.com/app/apple-store/id1512328590?pt=118010433))
 - [Sweepy](https://sweepy.app/)