Update README.md

Author: Pythack

README.md

@@ -17,10 +17,14 @@
 <a text-align="center" href="https://addons.mozilla.org/en-GB/firefox/addon/selection-customizer/"><img alt="Get for Firefox" src="https://addons.cdn.mozilla.net/static/img/addons-buttons/AMO-button_1.png" width="172" height="60"></a> or <a href="https://addons.mozilla.org/firefox/downloads/file/3775633/selection_customizer-1.1-fx.xpi">install now</a> !
 
 ## Features
+### Available
 * Change the text color of the text selection
 * Change the background color of the selection
 * View live preview while editing
 
+### In development
+* Change the undeline style of the selection
+
 # Screenshots
 <img alt="Screenshot settings_page" src="https://pythack.github.io/Selection-customizer/settings%20page.png">
 <img alt="Screenshot settings_page" src="https://pythack.github.io/Selection-customizer/google%20demo.png">