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/sys/wezterm.go

@@ -1,14 +1,14 @@
 package sys
 
 import (
-	"github.com/versenilvis/iris/commands/core"
+	"github.com/versenilvis/iris/spec"
 )
 
 func init() {
-	core.Register(&core.Spec{
+	spec.Register(&spec.Spec{
 		Name:        "wezterm",
 		Description: "Wez",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "start", Description: "Start the GUI, optionally running an alternative program"},
 			{Name: "ssh", Description: "Establish an ssh session"},
 			{Name: "serial", Description: "Open a serial port"},
@@ -27,7 +27,7 @@ func init() {
 			{Name: "replay", Description: "Replay an asciicast terminal session"},
 			{Name: "shell-completion", Description: "Generate shell completion information"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "--cwd", Description: "Specify the current working directory for the initially spawned program"},
 			{Name: "--class", Description: "Override the position for the initial window launched by this process"},
 			{Name: "--no-auto-connect", Description: "Print help information"},