Update readme

README.md

@@ -4,6 +4,23 @@ Kotlin compiler plugin that adds `shallowSize` extension property to all data cl
 
 ## Getting started
 
+### Usage
+
+Kotlin 1.5.0 is supported.
+
+1. Download `.jar` from release assets.
+2. Add compiler option in `build.gradle.kts`:
+
+```kotlin
+kotlinOptions {
+    freeCompilerArgs = listOf(
+        "-Xplugin=/path/to/core-1.0-SNAPSHOT.jar",
+        "-P",
+        "plugin:arrow.meta.plugin.compiler:generatedSrcOutputDir=${buildDir}"
+    )
+}
+```
+
 ### Development
 
 ```bash