Open source API portal now generally availabile

Open source API portal key features include: * A drag-and-drop visual editor to customize the portal without writing code. * A GitHub-based API ecosystem including automated deployments with GitHub Actions and free hosting with GitHub Pages. This open source project is available on [GitHub](https://github.com/Azure/API-Portal) and is licensed under the [MIT license](https://github.com/Azure/API-Portal/blob/main/LICENSE). It utilizes the same key technologies as Azure API Management's developer portal, which is used by thousands of Azure customers. [Learn more](https://github.com/Azure/API-Portal). * API Management * Features * [ API Management](https://azure.microsoft.com/en-gb/products/api-management/)