Updated README.md

Author: topnax

README.md

@@ -1,10 +1,12 @@
 # Crypto Portfolio Tracker
 A tracker of your crypto portfolio, written in C# using .NET core. Made as KIV/NET semester project at Západočeská univerzita v Plzni.
+![Application screenshot](doc/img/cpt-screenshots/portfolio-entry-detail.png)
 ## Features
 - create and manage portfolios
 - create and manage portfolio entries
 - add transactions that are linked to portfolio entries
 - see summaries of portfolios, portfolio entries and transactions
+    - based on current cryptocurrency market data fetched from [CoinGecko](https://www.coingecko.com/en/api)
 ## Electron
 ```electronize start /PublishSingleFile false /PublishReadyToRun false --no-self-contained```