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/herd.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:        "herd",
 		Description: "Display this application version",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "phpVersion", Description: "The PHP version you want to use; e.g 8.1"},
 			{Name: "nodeVersion", Description: "The Node version you want to use; e.g 21"},
 			{Name: "links", Description: "Display all of the registered Herd links"},
@@ -16,7 +16,7 @@ func init() {
 			{Name: "namespace", Description: "The namespace name"},
 			{Name: "site", Description: "The site to get the PHP executable path for"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "--help", Description: "Display this application version"},
 			{Name: "--quiet", Description: "Do not output any message"},
 			{Name: "--verbose", Description: "Force ANSI output"},