Update README.md

Enable CInteropCommonization in gradle level.

Author: wh173d3v11

README.md

@@ -41,6 +41,12 @@ buildscript {
 }
 
 apply(plugin = "io.github.ttypic.swiftklib")
+```
+Add this to the project-level gradle.properties file (if it’s not already included).
+```properties
+#Kotlin Multiplatform
+kotlin.mpp.enableCInteropCommonization=true
+
 ```
 
 ## Usage