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/forc.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:        "forc",
 		Description: "Fuel Orchestrator",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "addr2line", Description: "Show location and context of an opcode address in its source file"},
 			{Name: "build", Description: "Compile the current or target project"},
 			{Name: "check", Description: "Check the current or target project and all of its dependencies for errors"},
@@ -40,7 +40,7 @@ func init() {
 			{Name: "submit", Description: "A `forc` plugin for interacting with a Fuel node"},
 			{Name: "deploy", Description: "Build output file options"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "-S", Description: "Where to search for the project root"},
 			{Name: "-g", Description: "Source file mapping in JSON format"},
 			{Name: "-c", Description: "How many lines of context to show"},