Improve YAML documentation with Bun.YAML.stringify and TypeScript typing

- Add Bun.YAML.stringify() documentation with examples using (null, 2) for spacing
- Document space parameter: 2 for readable format, 0 for compact flow style
- Add TypeScript section in Module Import explaining manual .d.ts requirement
- Clarify that unlike JSON, TypeScript doesn't automatically type YAML imports
- Show comprehensive example with nested objects, arrays, and objects in arrays
- Demonstrate YAML anchors & aliases with shared object references
- Fix heading structure: parse examples under parse, stringify as separate section
- Use actual tested Bun output for all examples

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: Claude Bot

docs/runtime/yaml.mdx

@@ -121,6 +121,44 @@ try {
 }
 ```
 
+### `Bun.YAML.stringify()`
+
+Convert a JavaScript object into a YAML string.
+
+```ts
+import { YAML } from "bun";
+
+const obj = {
+  name: "John Doe",
+  age: 30,
+  email: "[email protected]",
+  hobbies: ["reading", "coding", "hiking"]
+};
+
+const yaml = Bun.YAML.stringify(obj, null, 2);
+console.log(yaml);
+// name: John Doe
+// age: 30
+// email: [email protected]
+// hobbies:
+//   - reading
+//   - coding
+//   - hiking
+```
+
+The signature is similar to `JSON.stringify()`:
+
+```ts
+Bun.YAML.stringify(value, replacer?, space?)
+```
+
+The `space` parameter controls indentation (default: 2). With `space: 0`, YAML outputs in compact flow style on a single line:
+
+```ts
+const compact = Bun.YAML.stringify(obj, null, 0);
+// {name: John Doe,age: 30,email: [email protected],hobbies: [reading,coding,hiking]}
+```
+
 ---
 
 ## Module Import
@@ -193,6 +231,30 @@ const { database, redis } = require("./config.yaml");
 console.log(database.port); // 5432
 ```
 
+### TypeScript
+
+Unlike JSON files, TypeScript doesn't automatically type YAML imports. Add type definitions by creating a `.d.ts` file with the same name as your YAML file:
+
+```ts config.yaml.d.ts icon="/icons/typescript.svg"
+const contents: {
+  database: {
+    host: string;
+    port: number;
+    name: string;
+  };
+  server: {
+    port: number;
+    timeout: number;
+  };
+  features: {
+    auth: boolean;
+    rateLimit: boolean;
+  };
+};
+
+export = contents;
+```
+
 ---
 
 ## Hot Reloading with YAML
@@ -435,6 +497,76 @@ if (parseConfig(migrations).autoRun === "true") {
 }
 ```
 
+### Generating YAML Files
+
+You can use `Bun.YAML.stringify()` to programmatically create YAML configuration files. It handles complex data structures including nested objects, arrays, and objects within arrays. When you reference the same object multiple times, YAML automatically creates anchors (`&`) and aliases (`*`) to avoid duplication:
+
+<CodeGroup>
+```ts generate-config.ts icon="/icons/typescript.svg"
+import { YAML } from "bun";
+
+const defaults = {
+  timeout: 30000,
+  retries: 3,
+};
+
+const config = {
+  defaults,
+  development: {
+    defaults,
+    host: "localhost",
+    port: 3000,
+  },
+  production: {
+    defaults,
+    host: "api.example.com",
+    port: 443,
+  },
+  servers: [
+    { name: "server1", url: "https://api1.example.com" },
+    { name: "server2", url: "https://api2.example.com" },
+  ],
+  features: {
+    enabled: ["auth", "logging", "metrics"],
+    disabled: ["experimental"],
+  },
+};
+
+// Generate readable YAML with 2-space indentation
+const yaml = Bun.YAML.stringify(config, null, 2);
+await Bun.write("config.yaml", yaml);
+```
+
+```yaml output.yaml icon="file-code"
+defaults:
+  &defaults
+  timeout: 30000
+  retries: 3
+development:
+  defaults:
+    *defaults
+  host: localhost
+  port: 3000
+production:
+  defaults:
+    *defaults
+  host: api.example.com
+  port: 443
+servers:
+  - name: server1
+    url: https://api1.example.com
+  - name: server2
+    url: https://api2.example.com
+features:
+  enabled:
+    - auth
+    - logging
+    - metrics
+  disabled:
+    - experimental
+```
+</CodeGroup>
+
 ### Bundler Integration
 
 When you import YAML files in your application and bundle it with Bun, the YAML is parsed at build time and included as a JavaScript module: