docs(installation): add missing pgrx initialization and database connection steps

docs/installation.md

@@ -1,15 +1,37 @@
-First, install [pgrx](https://github.com/tcdi/pgrx) by running `cargo install --locked cargo-pgrx@version`, where version should be compatible with the [pgrx version used by pg_graphql](https://github.com/supabase/pg_graphql/blob/master/Cargo.toml#L16)
+First, install [pgrx](https://github.com/tcdi/pgrx) by running `cargo install --locked cargo-pgrx@version`, where version should be compatible with the [pgrx version used by pg_graphql](https://github.com/supabase/pg_graphql/blob/master/Cargo.toml#L16).
 
-Then clone the repo and install using
+Then clone the repo and install using:
 
 ```bash
 git clone https://github.com/supabase/pg_graphql.git
 cd pg_graphql
 cargo pgrx install --release
 ```
 
-To enable the extension in PostgreSQL we must execute a `create extension` statement. The extension creates its own schema/namespace named `graphql` to avoid naming conflicts.
+Before enabling the extension you need to initialize `pgrx`. The easiest way to get started is to allow `pgrx` to manage its own version/s of Postgres:
+
+```bash
+cargo pgrx init --pg16=download
+```
+
+For more advanced configuration options, like building against an existing Postgres installation from e.g. Homebrew, see the [pgrx docs](https://github.com/pgcentralfoundation/pgrx)
+
+To start the database:
+
+```bash
+cargo pgrx start pg16
+```
+
+To connect:
+
+```bash
+cargo pgrx connect pg16
+```
+
+Finally, to enable the `pg_graphql` extension in Postgres, execute the `create extension` statement. This extension creates its own schema/namespace named `graphql` to avoid naming conflicts.
 
 ```psql
 create extension pg_graphql;
 ```
+
+These steps ensure that `pgrx` is properly initialized, and the database is started and connected before attempting to install and use the `pg_graphql` extension.