docs: Document pgai gem use for thin clone access

doc/development/database/database_lab.md

@@ -130,6 +130,79 @@ For information on testing migrations, review our
 
 ### Access the console with `psql`
 
+NOTE:
+You must have `AllFeaturesUser` [`psql` access](#access-database-lab-engine) to access the console with `psql`.
+
+#### Simplified access through `pgai` Ruby gem
+
+[@mbobin](https://gitlab.com/mbobin) created the [`pgai` Ruby Gem](https://gitlab.com/mbobin/pgai/#pgai) that
+greatly simplifies access to a database clone, with support for:
+
+- Access to all database clones listed in the [Postgres.ai instances page](https://console.postgres.ai/gitlab/instances);
+- Multiple `psql` sessions on the same clone.
+
+If you have `AllFeaturesUser` [`psql` access](#access-database-lab-engine), you can follow the steps below to configure
+the `pgai` Gem:
+
+1. To get started, you need to gather some values from the [Postgres.ai instances page](https://console.postgres.ai/gitlab/instances):
+
+   1. Navigate to the instance that you want to configure and the on right side of the screen.
+   1. Under **Connection**, select **Connect**. The menu might be collapsed.
+
+      A pop-up with everything that's needed for configuration appears, using this format:
+
+      ```shell
+      dblab init --url http://127.0.0.1:1234 --token TOKEN --environment-id <environment-id>
+      ```
+
+      ```shell
+      ssh -NTML 1234:localhost:<environment-port> <postgresai-user>@<postgresai-proxy> -i ~/.ssh/id_rsa
+      ```
+
+1. Add the following snippet to your SSH configuration file at `~/.ssh/config`, replacing the variable values:
+
+   ```plaintext
+   Host pgai-proxy
+     HostName <postgresai-proxy>
+     User <postgresai-user>
+     IdentityFile ~/.ssh/id_ed25519
+   ```
+
+1. Run the following command so you can accept the server key fingerprint:
+
+   ```shell
+   ssh pgai-proxy
+   ```
+
+1. Run the following commands:
+
+   ```shell
+   gem install pgai
+
+   # Grab an access token: https://console.postgres.ai/gitlab/tokens
+   # GITLAB_USER is your GitLab handle
+   pgai config --dbname=gitlabhq_dblab --prefix=$GITLAB_USER --proxy=pgai-proxy
+
+   # Grab the respective port values from https://console.postgres.ai/gitlab/instances
+   # for the instances you'll be using (in this case, for the `main` database instance)
+   pgai env add --alias main --id <environment-id> --port <environment-port>
+   ```
+
+1. Once this one-time configuration is done, you can use `pgai connect` to connect to a particular database. For
+   instance, to connect to the `main` database:
+
+   ```shell
+   pgai connect main
+   ```
+
+1. Once done with the clone, you can destroy it:
+
+   ```shell
+   pgai destroy main
+   ```
+
+#### Manual access through the Postgres.ai instances page
+
 Team members with [`psql` access](#access-database-lab-engine), can gain direct access
 to a clone via `psql`. Access to `psql` enables you to see data, not just metadata.