chore: rename keystone to draft

Rename the module, CLI command name, and all references from
keystone/basalt to draft, and fix the stale build/README content
found along the way.

cmd/version.go

@@ -15,9 +15,9 @@ func init() {
 
 var versionCmd = &cobra.Command{
 	Use:   "version",
-	Short: "Display the version of Keystone",
-	Long:  `Display the current version of the Keystone CLI tool.`,
+	Short: "Display the version of Draft",
+	Long:  `Display the current version of the Draft CLI tool.`,
 	Run: func(cmd *cobra.Command, args []string) {
-		fmt.Printf("Keystone CLI version: %s\n", version)
+		fmt.Printf("Draft CLI version: %s\n", version)
 	},
 }