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/mongosh.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:        "mongosh",
 		Description: "Default Connection String; Equivalent to running mongosh without any commands",
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "-v", Description: "View your current mongosh version"},
 			{Name: "--shell", Description: "Returns information on the options and use of the MongoDB Shell"},
 			{Name: "--authenticationDatabase", Description: "This option is available only in MongoDB Enterprise"},