Add tutorial section to docs/README.md

docs/README.md

@@ -12,7 +12,44 @@
 
 ## Installation
 
-## Getting started
+## Tutorial
+
+This section will walk you through applying your first migrations using `pgroll`.
+
+Prerequisites:
+
+* `pgroll` installed and accessible somewhere on your `$PATH`
+* A fresh Postgres instance against which to run migrations.
+
+A good way to get a throw-away Postgres instance for use in the tutorial is to use [Docker](https://www.docker.com/). Start a Postgres instance in Docker with:
+
+```
+docker run --rm --name for-pgroll -e POSTGRES_PASSWORD=postgres -p 5432:5432 -d postgres:16
+```
+
+The remainder of the tutorial assumes that you have a local Postgres instance accessible on port 5432.
+
+### Initialization
+
+`pgroll` needs to store its own internal state somewhere in the target Postgres instance. Initializing `pgroll` configures this store and makes `pgroll` ready for first use:
+
+```
+pgroll init
+```
+
+You should see a success message indicating that `pgroll` has been configured.
+
+<details>
+  <summary>**What data does pgroll store**?</summary>
+
+  ## Heading
+  1. A numbered list item
+  2. Another numbered list item
+
+  ```go
+  fmt.Println("Hello, world!")
+  ```
+</details>
 
 ## Command line reference