update changeset with @sarah11918 suggestions

.changeset/lovely-pianos-breathe.md

@@ -2,9 +2,11 @@
 'astro': minor
 ---
 
-Adds support for custom parsers to file loader
+Adds a new optional `parser` property to the built-in `file()` loader for content collections to support additional file types such as `toml` and `csv`.
 
-For example, with a toml file of this format:
+The `file()` loader now accepts a second argument that defines a `parser` function. This allows you to specify a custom parser (e.g. `toml.parse` or `csv-parse`) to create a collection from a file's contents. The `file()` loader will automatically detect and parse JSON and YAML files (based on their file extension) with no need for a `parser`.
+
+This works with any type of custom file formats including `csv` and `toml`. The following example defines a content collection `dogs` using a `.toml` file.
 ```toml
 [[dogs]]
 id = "..."
@@ -14,27 +16,53 @@ age = "..."
 id = "..."
 age = "..."
 ```
-a content collection using this file could look like this
+After importing TOML's parser, you can load the `dogs` collection into your project by passing both a file path and `parser` to the `file()` loader.
 ```typescript
 import { defineCollection } from "astro:content"
 import { file } from "astro/loaders"
 import { parse as parseToml } from "toml"
+
 const dogs = defineCollection({
   loader: file("src/data/dogs.toml", { parser: (text) => parseToml(text).dogs }),
   schema: /* ... */
 })
+
+// it also works with CSVs!
+import { parse as parseCsv } from "csv-parse/sync";
+
+const cats = defineCollection({
+  loader: file("src/data/cats.csv", { parser: (text) => parseCsv(text, { columns: true, skipEmptyLines: true })})
+});
 ```
 
-This also adds support for nested json documents. For example:
+The `parser` argument also allows you to load a single collection from a nested JSON document. For example, this JSON file contains multiple collections:
 ```json
 {"dogs": [{}], "cats": [{}]}
 ```
-can be consumed using
+
+You can seperate these collections by passing a custom `parser` to the `file()` loader like so:
 ```typescript
 const dogs = defineCollection({
   loader: file("src/data/pets.json", { parser: (text) => JSON.parse(text).dogs })
-})
+});
 const cats = defineCollection({
   loader: file("src/data/pets.json", { parser: (text) => JSON.parse(text).cats })
-})
+});
+```
+
+```typescript
+```
+
+And it continues to work with maps of `id` to `data`
+```yaml
+bubbles:
+  breed: "Goldfish"
+  age: 2
+finn:
+  breed: "Betta"
+  age: 1
+```
+
+```typescript
+const fish = defineCollection({ loader: file("src/data/fish.yaml"), schema: z.object({ breed: z.string(), age: z.number() }) });
 ```