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/js/remix.go

@@ -1,20 +1,20 @@
 package js
 
 import (
-	"github.com/versenilvis/iris/commands/core"
+	"github.com/versenilvis/iris/spec"
 )
 
 func init() {
-	core.Register(&core.Spec{
+	spec.Register(&spec.Spec{
 		Name:        "remix",
 		Description: "Represent the directory of the Remix application",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "build", Description: "Create an optimized production build of your application"},
 			{Name: "dev", Description: "Start the application in development mode"},
 			{Name: "setup", Description: "Prepare node_modules/remix folder (after installation of packages)"},
 			{Name: "routes", Description: "Generate the route config of the application"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "--help", Description: "Output usage information"},
 			{Name: "-v", Description: "Output the version number"},
 			{Name: "--sourcemap", Description: "Enables production sourcemap"},