Fix typo in english grammar rule for type VOID

grammar/en/ivprog.ts

@@ -19,7 +19,7 @@ const types: I18N_LEXER_TYPES = {
 };
 const commands: I18N_LEXER_COMMANDS = {
   // RK_VOID is not formally part of Types since it doesn't have a valid value/instance
-  RK_VOID: "vazio",
+  RK_VOID: "void",
   // commands
   RK_PROGRAM: "program",
   RK_SWITCH: "switch",