Readme and screenshots update

README.md

@@ -1,5 +1,6 @@
-# Look4Sat
-Amateur radio & weather satellites passes calculator for Android. Inspired by [Gpredict](http://gpredict.oz9aec.net/) from [Alexandru Csete, OZ9AEC](https://github.com/csete). Using the mavenized version of [predict4java](https://github.com/davidmoten/predict4java) lib under the hood created by [David A. B. Johnson, G4DPZ](https://github.com/g4dpz) and [Dave Moten](https://github.com/davidmoten).
+# Look4Sat: Radio satellite tracker
+Ham radio and weather satellite tracker and passes predictor inspired by [Gpredict](http://gpredict.oz9aec.net/) from [Alexandru Csete, OZ9AEC](https://github.com/csete).  
+Using the mavenized version of [predict4java](https://github.com/davidmoten/predict4java) lib under the hood created by [David A. B. Johnson, G4DPZ](https://github.com/g4dpz) and [Dave Moten](https://github.com/davidmoten).
 
 The app is built using Dagger2, Retrofit2, Kotlin and Kotlin coroutines, Architecture Components and Jetpack Navigation.
 
@@ -9,3 +10,13 @@ The app is built using Dagger2, Retrofit2, Kotlin and Kotlin coroutines, Archite
 <img src="screenshots/scr_pass_view.jpg" width="250"/>
 </p>
 <img src="screenshots/scr_world_map.jpg" width="750">
+
+## Main features: 
+
+– Calculating satellite passes for up to one week (168 hours)  
+– Calculating passes for the current or manually entered location  
+– Showing the list of currently active and upcoming satellite passes  
+– Showing the active pass progress, polar trajectory and transceivers info  
+– Showing the satellite positional data, footprint and ground track on a map  
+– Offline first: pass prediction is done offline. It's up to you to decide when  
+to update the TLE file and the transceivers DB. (Updates once a week are recommended)