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/create_completion_spec.go

@@ -1,17 +1,17 @@
 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:        "create-completion-spec",
 		Description: "Setup fig folder and create spec with the given name",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "help", Description: "Display help for command"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "--here", Description: "Set if the spec should be created in the current folder"},
 			{Name: "-h", Description: "Display help for command"},
 		},