feat: migrate to ESM

docs/src/creating-parsers/1-getting-started.md

@@ -64,7 +64,7 @@ There should be a file called `grammar.js` with the following contents:
 /// <reference types="tree-sitter-cli/dsl" />
 // @ts-check
 
-module.exports = grammar({
+export default grammar({
   name: 'LOWER_PARSER_NAME',
 
   rules: {

docs/src/creating-parsers/3-writing-the-grammar.md

@@ -313,7 +313,7 @@ A construct like `[x, y]` could be legitimately parsed as both an array literal
 pattern (like in `let [x, y] = arr`).
 
 ```js
-module.exports = grammar({
+export default grammar({
   name: "javascript",
 
   rules: {