Update README

Author: asus4

README.md

@@ -1,3 +1,9 @@
 # Unity Native Dialog Plugin
 
-Show iOS / Android native dialog from Unity.
+Displays iOS / Android native dialog from Unity.
+
+## Install via UPM
+
+Add the following GitHub URL from the Package Manager UI
+
+`https://github.com/asus4/UnityNativeDialogPlugin.git?path=/Packages/com.github.asus4.nativedialog#v1.0.0`