Add compiler plugin example to readme

Author: tschuchortdev

README.md

@@ -52,6 +52,9 @@ Configure compilation
 
         // pass your own instance of an annotation processor
         annotationProcessors = listOf(MyAnnotationProcessor()) 
+
+        // pass your own instance of a compiler plugin
+        compilerPlugins = listOf(MyComponentRegistrar())
 
         inheritClassPath = true
         messageOutputStream = System.out // see diagnostics in real time