refactor(commands): separate commands and its core into two folders (#32)

- I think it would be better if one for commands only, one for the spec
handling core logic so people won't be confused by the core logic inside
the commands folder (cleaner I guess)
- Regen docs

commands/sys/simctl.go

@@ -1,14 +1,14 @@
 package sys
 
 import (
-	"github.com/versenilvis/iris/commands/core"
+	"github.com/versenilvis/iris/spec"
 )
 
 func init() {
-	core.Register(&core.Spec{
+	spec.Register(&spec.Spec{
 		Name:        "simctl",
 		Description: "Add photos, live photos, videos, or contacts to the library of a device",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "addmedia", Description: "Add photos, live photos, videos, or contacts to the library of a device"},
 			{Name: "boot", Description: "Boot a device or device pair"},
 			{Name: "clone", Description: "Clone an existing device"},
@@ -60,7 +60,7 @@ func init() {
 			{Name: "terminate", Description: "Terminate an application by identifier on a device"},
 			{Name: "ui", Description: "Get or Set UI options"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "--arch", Description: "Clone an existing device"},
 			{Name: "-b", Description: "Do NOT show the resulting archive in a Finder window upon completion"},
 			{Name: "-X", Description: "Specify a duration (in seconds) to wait for the log collection before timeout"},