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/trunk.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:        "trunk",
 		Description: "Run on all files instead of only changed files",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "init", Description: "Setup trunk in this repo"},
 			{Name: "check", Description: "Universal code checker"},
 			{Name: "upgrade", Description: "Upgrade all linters to latest versions"},
@@ -28,7 +28,7 @@ func init() {
 			{Name: "shutdown", Description: "Shutdown the trunk daemon if it is running"},
 			{Name: "status", Description: "Report daemon status"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "-a", Description: "Run on all files instead of only changed files"},
 			{Name: "-n", Description: "Don't automatically apply fixes"},
 			{Name: "--include-existing-autofixes", Description: "Show autofixes for existing issues"},