Add 5.9 release announcement (#17)

* Add 5.9 release announcement

* Update 5-9-released.md

Author: kateinoigakukun

Content/posts/5-9-released.md

@@ -0,0 +1,41 @@
+---
+date: 2024-01-16 20:00
+description: SwiftWasm 5.9.1 has been released.
+---
+
+# SwiftWasm 5.9.1 is now available
+
+We're happy to announce the new release of SwiftWasm tracking upstream Swift 5.9.1!
+
+This is a periodic release of SwiftWasm, which tracks the upstream Swift 5.9.1 release.
+As for changes in upstream Swift 5.9, we recommend referring [to the official
+changelog](https://github.com/apple/swift/blob/swift-5.9.1-RELEASE/CHANGELOG.md#swift-59).
+
+For more information about SwiftWasm in general and for getting started, please visit [the project documentation](https://book.swiftwasm.org/).
+If you have any questions, please come and talk to us on [the SwiftWasm discussion forums](https://github.com/swiftwasm/swift/discussions)
+or [open an issue](https://github.com/swiftwasm/swift/issues/new)!
+
+## Internal build infrastructure changes
+
+We've made some changes to our internal build infrastructure, which should make it easier for us to
+track upstream Swift changes. Now GitHub [swiftwasm/swift](https://github.com/swiftwasm/swift) repository
+is just for hosting our release artifacts, and we're maintaining our downstream changes in traditional `.patch`
+file format in [swiftwasm/swiftwasm-build](https://github.com/swiftwasm/swiftwasm-build) repository. See [our rationale](https://github.com/swiftwasm/swiftwasm-build/blob/main/docs/faq.md) if you're interested in the details of this decision.
+
+## Acknowledgements
+
+We'd like to thank [our GitHub sponsors](https://github.com/sponsors/swiftwasm) and [OpenCollective
+contributors](https://opencollective.com/swiftwasm) for their support, which allowed us to continue working on SwiftWasm
+and related projects. We are displaying our gold sponsors on the README of [swiftwasm/swift](https://github.com/swiftwasm/swift) repository.
+If you are already a gold sponsor and not yet listed, please [contact Yuta Saito](https://twitter.com/kateinoigakukun) to add your appropriate logo.
+
+We're committed to publishing transparent and open finances, so all expenses and transactions can be
+viewed publicly on our [OpenCollective Transactions](https://opencollective.com/swiftwasm/transactions) page.
+
+So far we've spent money on monthly CI bills that cover new `aarch64` CPU architecture and [community CI](https://ci-external.swift.org/job/oss-swift-RA-linux-ubuntu-20.04-webassembly),
+domain registration, email hosting, and development hardware for our maintainers.
+
+Many thanks to [MacStadium](https://www.macstadium.com) for giving us access to Apple Silicon hardware.
+
+Additionally, we'd like to thank everyone who contributed their work and helped us make this release
+happen. These new releases wouldn't be possible without the hard work of them and the Swift community as a whole.