Update README.md

Author: typicode

README.md

@@ -1,3 +1,7 @@
 ## Try it
 
 [https://my-json-server.typicode.com/typicode/demo](https://my-json-server.typicode.com/typicode/demo)
+
+## Use your own data
+
+Fork it and change `db.json` values or create a repo with a `db.json` file.