neon_local: improved docs and fix wrong connstr (#6954)

The user created with the `--create-test-user` flag is `test` instead of
`user`.

ref https://github.com/neondatabase/neon/pull/6848

Signed-off-by: Alex Chi Z <chi@neon.tech>

README.md

@@ -230,6 +230,8 @@ postgres=# select * from t;
 > cargo neon stop
 ```
 
+More advanced usages can be found at [Control Plane and Neon Local](./control_plane/README.md).
+
 #### Handling build failures
 
 If you encounter errors during setting up the initial tenant, it's best to stop everything (`cargo neon stop`) and remove the `.neon` directory. Then fix the problems, and start the setup again.

control_plane/README.md

@@ -0,0 +1,26 @@
+# Control Plane and Neon Local
+
+This crate contains tools to start a Neon development environment locally. This utility can be used with the `cargo neon` command.
+
+## Example: Start with Postgres 16
+
+To create and start a local development environment with Postgres 16, you will need to provide `--pg-version` flag to 3 of the start-up commands.
+
+```shell
+cargo neon init --pg-version 16
+cargo neon start
+cargo neon tenant create --set-default --pg-version 16
+cargo neon endpoint create main --pg-version 16
+cargo neon endpoint start main
+```
+
+## Example: Create Test User and Database
+
+By default, `cargo neon` starts an endpoint with `cloud_admin` and `postgres` database. If you want to have a role and a database similar to what we have on the cloud service, you can do it with the following commands when starting an endpoint.
+
+```shell
+cargo neon endpoint create main --pg-version 16 --update-catalog true
+cargo neon endpoint start main --create-test-user true
+```
+
+The first command creates `neon_superuser` and necessary roles. The second command creates `test` user and `neondb` database. You will see a connection string that connects you to the test user after running the second command.

control_plane/src/endpoint.rs

@@ -605,7 +605,7 @@ impl Endpoint {
         let conn_str = self.connstr("cloud_admin", "postgres");
         println!("Starting postgres node at '{}'", conn_str);
         if create_test_user {
-            let conn_str = self.connstr("user", "neondb");
+            let conn_str = self.connstr("test", "neondb");
             println!("Also at '{}'", conn_str);
         }
         let mut cmd = Command::new(self.env.neon_distrib_dir.join("compute_ctl"));