Add Swift 5.8, increase template version number (#19)

* Add 5.8 increase version number

* Update README

Author: adam-fowler

README.md

@@ -8,7 +8,7 @@ Develop Swift based applications. Includes everything you need to get up and run
 
 | Options Id | Description | Type | Default Value |
 |-----|-----|-----|-----|
-| imageVariant | Version of Swift | string | 5.7 |
+| imageVariant | Version of Swift | string | 5.8 |
 
 This template uses the common-utils feature to implement some commonly implemented options including install zsh and updating packages. Edit the values in the `devcontainer.json` to enable these. More details on available options can be found [here](https://github.com/devcontainers/features/blob/main/src/common-utils/README.md). 
 

src/swift/devcontainer-template.json

@@ -1,6 +1,6 @@
 {
 	"id": "swift",
-	"version": "2.0.0",
+	"version": "2.1.0",
 	"name": "Swift",
 	"description": "Develop Swift based applications. Includes everything you need to get up and running.",
 	"documentationURL": "https://github.com/swift-server/swift-devcontainer-template/tree/main/README.md",
@@ -11,6 +11,7 @@
 			"type": "string",
 			"description": "Swift version:",
 			"proposals": [
+				"5.8",
 				"5.7",
 				"5.6-focal",
 				"5.5",
@@ -19,7 +20,7 @@
 				"5.2",
 				"5.1"
 			],
-			"default": "5.7"
+			"default": "5.8"
 		}
 	},
 	"platforms": [