docs: document checks examples + migrations naming convention (#13052)

www/apps/book/app/learn/fundamentals/data-models/properties/page.mdx

@@ -58,6 +58,32 @@ const Post = model.define("post", {
 export default Post
 ```
 
+#### Limit Text Length
+
+To limit the allowed length of a `text` property, use the [checks method](../check-constraints/page.mdx).
+
+For example, to limit the `name` property to a maximum of 50 characters:
+
+export const textLengthHighlights = [
+  ["7", "checks", "Add check constraints to the data model."],
+]
+
+```ts highlights={textLengthHighlights}
+import { model } from "@medusajs/framework/utils"
+
+const Post = model.define("post", {
+  name: model.text(),
+  // ...
+})
+.checks([
+  (columns) => `${columns.name.length} <= 50`,
+])
+
+export default Post
+```
+
+This will add a database check constraint that ensures the `name` property of a record does not exceed 50 characters. If a record with a longer `name` is attempted to be inserted, an error will be thrown.
+
 ### number
 
 The `number` method defines a number property.