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/rust/pijul.go

@@ -1,14 +1,14 @@
 package rust
 
 import (
-	"github.com/versenilvis/iris/commands/core"
+	"github.com/versenilvis/iris/spec"
 )
 
 func init() {
-	core.Register(&core.Spec{
+	spec.Register(&spec.Spec{
 		Name:        "pijul",
 		Description: "Adds a path to the tree",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "add", Description: "Adds a path to the tree"},
 			{Name: "PATHS", Description: "Paths to add to the internal tree"},
 			{Name: "apply", Description: "Applies changes to a channel"},
@@ -42,7 +42,7 @@ func init() {
 			{Name: "unrecord", Description: "Unrecords a list of changes"},
 			{Name: "CHANGE_ID", Description: "The hash of a change (unambiguous prefixes are accepted)"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "-f", Description: "Print help information"},
 			{Name: "-r", Description: "Applies changes to a channel"},
 			{Name: "--channel", Description: "Apply change to this channel"},