chore(docs): 4.9 Release Notes (#34999)

docs/docs/how-to/custom-configuration/typescript.md

@@ -192,6 +192,7 @@ type Person = {
 export const sourceNodes: GatsbyNode["sourceNodes"] = async ({
   actions,
   createNodeId,
+  createContentDigest,
 }) => {
   const { createNode } = actions
 

docs/docs/reference/release-notes/v4.9/index.md

@@ -0,0 +1,100 @@
+---
+date: "2022-03-01"
+version: "4.9.0"
+title: "v4.9 Release Notes"
+---
+
+Welcome to `gatsby@4.9.0` release (March 2022 #1)
+
+Key highlights of this release:
+
+- [Support for TypeScript in `gatsby-config` and `gatsby-node`](#support-for-typescript-in-gatsby-config-and-gatsby-node)
+
+Also check out [notable bugfixes](#notable-bugfixes--improvements).
+
+**Bleeding Edge:** Want to try new features as soon as possible? Install `gatsby@next` and let us know
+if you have any [issues](https://github.com/gatsbyjs/gatsby/issues).
+
+[Previous release notes](/docs/reference/release-notes/v4.8)
+
+[Full changelog][full-changelog]
+
+---
+
+## Support for TypeScript in `gatsby-config` and `gatsby-node`
+
+In the last release we added [support for TypeScript in `gatsby-browser` and `gatsby-ssr`](/docs/reference/release-notes/v4.8/#support-for-typescript-in-gatsby-browser-and-gatsby-ssr) and as a follow-up we're introducing a much requested feature: Support for TypeScript in `gatsby-config` and `gatsby-node` 🎉
+
+When you try it out in your project, please give us feedback in the [accompanying RFC](https://github.com/gatsbyjs/gatsby/discussions/34613) on what you like, what doesn't work, and what you like to see in the future. **Note:** There are currently [some limitations](/docs/how-to/custom-configuration/typescript/#current-limitations) that you'll need to be aware of. In the [RFC](https://github.com/gatsbyjs/gatsby/discussions/34613) you can also read why we chose [Parcel](https://parceljs.org/) for this feature and how we did it.
+
+You can learn everything about this new feature on the [TypeScript and Gatsby documentation page](/docs/how-to/custom-configuration/typescript/) but here are two small examples of `gatsby-config` and `gatsby-node` with TypeScript:
+
+```ts:title=gatsby-config.ts
+import type { GatsbyConfig } from "gatsby"
+
+const config: GatsbyConfig = {
+  siteMetadata: {
+    title: "Your Title",
+  },
+  plugins: [],
+}
+
+export default config
+```
+
+```ts:title=gatsby-node.ts
+import type { GatsbyNode } from "gatsby"
+
+type Person = {
+  id: number
+  name: string
+  age: number
+}
+
+export const sourceNodes: GatsbyNode["sourceNodes"] = async ({
+  actions,
+  createNodeId,
+  createContentDigest,
+}) => {
+  const { createNode } = actions
+
+  const data = await getSomeData()
+
+  data.forEach((person: Person) => {
+    const node = {
+      ...person,
+      parent: null,
+      children: [],
+      id: createNodeId(`person__${person.id}`),
+      internal: {
+        type: "Person",
+        content: JSON.stringify(person),
+        contentDigest: createContentDigest(person),
+      },
+    }
+
+    createNode(node)
+  })
+}
+```
+
+You can also check out the [using-typescript](https://github.com/gatsbyjs/gatsby/tree/master/examples/using-typescript) and [using-vanilla-extract](https://github.com/gatsbyjs/gatsby/tree/master/examples/using-vanilla-extract) examples!
+
+## Notable bugfixes & improvements
+
+- `gatsby`
+  - Cache date formatting in LMDB cache for speed improvements, via [PR #34834](https://github.com/gatsbyjs/gatsby/pull/34834)
+  - Batch page dependency actions for speed improvements, via [PR #34856](https://github.com/gatsbyjs/gatsby/pull/34856)
+
+## Contributors
+
+A big **Thank You** to [our community who contributed][full-changelog] to this release 💜
+
+- [0xflotus](https://github.com/0xflotus)
+  - fix: small typo error [PR #34848](https://github.com/gatsbyjs/gatsby/pull/34848)
+  - chore(gatsby-plugin-image): update readme typo [PR #34847](https://github.com/gatsbyjs/gatsby/pull/34847)
+- [jamatz](https://github.com/jamatz): docs(gatsby): GatbsyImage -> GatsbyImage [PR #34914](https://github.com/gatsbyjs/gatsby/pull/34914)
+- [brherr](https://github.com/brherr): Update gatsby-config.js [PR #34924](https://github.com/gatsbyjs/gatsby/pull/34924)
+- [benackles](https://github.com/benackles): chore(docs): Update link to "How to create a Gatsby Starter" [PR #34937](https://github.com/gatsbyjs/gatsby/pull/34937)
+
+[full-changelog]: https://github.com/gatsbyjs/gatsby/compare/gatsby@4.9.0-next.0...gatsby@4.9.0