cli readme update (#521)

### What

Update the ndc-postgres-cli readme with the new commands.

Author: Gil Mizrahi

crates/cli/readme.md

@@ -18,3 +18,31 @@ Create a configuration in a new directory using the following commands:
    ```sh
    CONNECTION_URI='<postgres-connection-string>' cargo run --bin ndc-postgres-cli -- --context='<directory>' update
    ```
+
+## Upgrade a configuration
+
+An older configuration version (e.g. "v3") can be upgraded to a newer one using the `upgrade` command.
+
+```sh
+cargo run --bin ndc-postgres-cli -- upgrade --dir-from <DIR_FROM> --dir-to <DIR_TO>
+```
+
+## Native Operations
+
+Native Operations can be listed, added, and deleted using ndc-postgres-cli:
+
+```sh
+$ CONNECTION_URI='<postgres-connection-string>' cargo run --bin ndc-postgres-cli -- --context='<directory>' native-operation --help
+Commands on Native Operations
+
+Usage: hasura-ndc-postgres native-operation <COMMAND>
+
+Commands:
+  list    List the existing Native Operations
+  create  Create a new Native Operation from a SQL file
+  delete  Delete an existing Native Operation from the configuration
+  help    Print this message or the help of the given subcommand(s)
+
+Options:
+  -h, --help  Print help
+```