chore: import upstream snapshot with attribution

examples/forms with a variable number of fields/README.md

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+# Handling forms with a variable number of fields
+
+This example shows how to handle forms with a number of fields
+that is not known in advance, but depends on the contents of the database.
+
+## The model
+
+We have a database with a table
+`products` that contains the products,
+a table `orders` that contains the orders,
+and a table `order_items` that contains the items of each order.
+
+We want to display a form to create a new order, with a field for each product.
+
+We cannot know in advance how many products there are,
+so we cannot write a simple insert statement for `orders_items`,
+like
+
+```sql
+INSERT INTO order_items (product_id, quantity)
+VALUES (:product_1, :product_1_quantity);
+```
+
+Instead, we use a single POST variable of type array to store the
+product IDs and quantities, like so:
+
+```sql
+SELECT 
+    'product_quantity[]'   AS name,
+    'Quantity of ' || name AS label
+FROM products
+```
+
+And then we parse the array in SQLite with the [JSON_EACH](https://www.sqlite.org/json1.html#jeach) function.
+
+## Screenshots
+
+![](./screenshots/home.png)
+![](./screenshots/order-form.png)
+![](./screenshots/order.png)