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/railway.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:        "railway",
 		Description: "CLI for managing Railway Apps",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "add", Description: "Add a plugin to your project"},
 			{Name: "completion", Description: "Generate shell-completions"},
 			{Name: "shell", Description: "The shell to generate completions for"},
@@ -45,7 +45,7 @@ func init() {
 			{Name: "version", Description: "Get the version of railway's CLI"},
 			{Name: "whoami", Description: "Get the logged in user"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "-e", Description: "Environment to delete from"},
 			{Name: "--browserless", Description: "Login without opening a browser"},
 			{Name: "-n", Description: "Output a specific number of lines"},