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/ops/flyctl.go

@@ -1,14 +1,14 @@
 package ops
 
 import (
-	"github.com/versenilvis/iris/commands/core"
+	"github.com/versenilvis/iris/spec"
 )
 
 func init() {
-	core.Register(&core.Spec{
+	spec.Register(&spec.Spec{
 		Name:        "flyctl",
 		Description: "Command line tool for Fly.io services",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "ping", Description: "Ping the Fly agent"},
 			{Name: "restart", Description: "Restart the Fly agent"},
 			{Name: "daemon-start", Description: "Run the Fly agent in the foreground"},
@@ -60,7 +60,7 @@ func init() {
 			{Name: "docs", Description: "View Fly documentation"},
 			{Name: "doctor", Description: "The DOCTOR command allows you to debug your Fly environment"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "--generate-name", Description: "Generate a name for the app"},
 			{Name: "--name", Description: "The app name to use"},
 			{Name: "--network", Description: "Specify custom network id"},