Update to go v1.16 and embed more extensive default blorg.org

Instead of the bare bones default config we embedded as a string until now we
can use go 1.16 embed to embed the test blorg.org which makes a much better
starting config (if only to see what's possible).

main.go

@@ -56,7 +56,7 @@ func runBlorg(args []string) {
 		if err := os.MkdirAll("content", os.ModePerm); err != nil {
 			log.Fatal(err)
 		}
-
+		log.Println("./blorg.org and ./content/ created. Please adapt ./blorg.org")
 	case "build":
 		config, err := blorg.ReadConfig(blorg.DefaultConfigFile)
 		if err != nil {