docs: update readme with screenshots

README.md

@@ -1,3 +1,18 @@
-# IptvPlayer
+# IPTV Player PWA
 
-Minimalistic IPTV application, basically developed as Chrome `Packaged App` to use on my Chromebook.
+|                       Select/upload a playlist                       |                   Main player interface                   |
+| :------------------------------------------------------------------: | :-------------------------------------------------------: |
+| ![List with added playlists and upload interface](./iptv-upload.png) | ![Sidebar with channel and video player](./iptv-main.png) |
+
+## Minimalistic IPTV application developed as a PWA to use on my Chromebook.
+
+**Features:**
+
+-   M3U8 playlists support
+-   Upload playlists from your file system
+-   Group-based channel list
+-   Search for channels
+-   Save channels as favorites
+-   PWA support
+
+*Note: Demo application deployed on GitHub Pages subdomain is not working correctly with the streams hosted in not secured context (http), because of the mixed-content policy.*