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/nhost.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:        "nhost",
 		Description: "Nhost",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "deploy", Description: "Deploy local migrations and metadata changes to Nhost production"},
 			{Name: "dev", Description: "Start Nhost project for local development"},
 			{Name: "down", Description: "Stop and remove local Nhost backend started by `nhost dev`"},
@@ -20,7 +20,7 @@ func init() {
 			{Name: "login", Description: "Login to your Nhost account"},
 			{Name: "logout", Description: "Logout from your Nhost account"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "--email", Description: "Email address"},
 		},
 	})