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/cc/swift.go

@@ -1,14 +1,14 @@
 package cc
 
 import (
-	"github.com/versenilvis/iris/commands/core"
+	"github.com/versenilvis/iris/spec"
 )
 
 func init() {
-	core.Register(&core.Spec{
+	spec.Register(&spec.Spec{
 		Name:        "swift",
 		Description: "Show help information",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "build", Description: "Build sources into binary products"},
 			{Name: "target", Description: "The name of the target to build"},
 			{Name: "product", Description: "The name of the product to build"},
@@ -60,7 +60,7 @@ func init() {
 			{Name: "compute-checksum", Description: "Compute the checksum for a binary artifact"},
 			{Name: "archive-source", Description: "Create a source archive for the package"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "--help", Description: "Show help information"},
 			{Name: "--version", Description: "Show the version"},
 			{Name: "-access-notes-path", Description: "Specify YAML file to override attributes on Swift declarations in this module"},