feat(config): add post-release event file

.rczrc.onrelease.js

@@ -1,4 +1,5 @@
 const fs = require("fs");
+const { execSync } = require("child_process");
 
 const packageFile = fs.readFileSync("./package.json").toString();
 const newPackageFile = packageFile.replace(
@@ -15,3 +16,7 @@ const newIndexFile = indexFile.replace(
 );
 
 fs.writeFileSync("./src/index.ts", newIndexFile);
+
+execSync(
+  `rcz changelog --show-hashes --unreleased-as v${__NEW_VERSION__} > CHANGELOG.md`
+);