update grid4 & heroledger models

heromodels/examples/heroledger_example/README.md

@@ -0,0 +1,15 @@
+# Heroledger Postgres Example
+
+This example demonstrates how to use the Heroledger `User` model against Postgres using the `heromodels::db::postgres` backend.
+
+- Connects to Postgres with user `postgres` and password `test123` on `localhost:5432`.
+- Creates the table and indexes automatically on first use.
+- Shows basic CRUD and an index lookup on `username`.
+
+Run it:
+
+```bash
+cargo run -p heromodels --example heroledger_example
+```
+
+Make sure Postgres is running locally and accessible with the credentials above.