feat: Add diff command

README.md

@@ -22,4 +22,4 @@ go build ./cmd/dot
 
 - [ ] Support compare directory
 - [ ] Switch to use lua for neovim config
-- [ ] Add diff command
+- [x] Add diff command

internal/cli/app.go

@@ -41,7 +41,7 @@ var (
 	installAliases = []string{"i"}
 	updateAliases  = []string{"u"}
 	cleanAliases   = []string{"c"}
-	compareAliases = []string{"cmp"}
+	compareAliases = []string{"cmp", "diff"}
 )
 
 // denyOSes contains OS which is not supported