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/doctl.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:        "doctl",
 		Description: "The official DigitalOcean command line interface (CLI)",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "help", Description: "Display help about commands"},
 			{Name: "get", Description: "Retrieve account profile details"},
 			{Name: "ratelimit", Description: "Retrieve your API usage and the remaining quota"},
@@ -60,7 +60,7 @@ func init() {
 			{Name: "db", Description: "Display commands for managing individual databases within a cluster"},
 			{Name: "maintenance-window", Description: "Display commands for scheduling automatic maintenance on your database cluster"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "-h", Description: "Help for doctl"},
 			{Name: "-v", Description: "Enable verbose output"},
 			{Name: "-o", Description: "Desired output format"},