Added showcase section to documentation (#3701)

docs/_sidebar.md

@@ -3,6 +3,7 @@
   - [Installing](/docs/Installing)
   - [Working Locally](/docs/WorkingLocally)
   - [Usage](/docs/Usage)
+  - [Showcases](/docs/Showcases)
 - Guide
   - [Top Level](/docs/top-level-api)
   - [Screen](/docs/screen-api)

docs/docs/showcases.md

@@ -0,0 +1,25 @@
+# Showcases
+
+### Playground
+
+The playground example is a place where we showcase and test all features of react-native-navigation.
+
+```bash
+git clone -b v2 git@github.com:wix/react-native-navigation.git
+cd react-native-navigation
+npm install
+npm run xcode # Opens XCode
+npm start # Starts the packager
+
+# Play the app in Simulator or on Device from within XCode
+```
+
+### Hekla for Hacker News
+
+A hacker news client built from the ground up with v2 of react-native-navigation. 
+
+It is a tab-based app and utilizes Split Layout for iOS tablets, 3D touch and more.
+
+- [Source code](https://github.com/birkir/hekla)
+- [Download iOS](https://itunes.apple.com/us/app/hekla/id1405096983?mt=8)
+- [Download Android](https://play.google.com/store/apps/details?id=is.pipe.hekla)