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

tests/integration_test.go

@@ -6,7 +6,7 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/versenilvis/iris/commands/core"
+	"github.com/versenilvis/iris/spec"
 	_ "github.com/versenilvis/iris/commands"
 )
 
@@ -35,7 +35,7 @@ func TestIntegration_ZoxideMultiWord(t *testing.T) {
 	t.Run("z matches multi-word folder without quotes", func(t *testing.T) {
 		// Simulating user typing "z My Awe"
 		input := "z My Awe"
-		results := core.Lookup(input)
+		results := spec.Lookup(input)
 		
 		found := false
 		for _, r := range results {