Update typings to support ESM (#141)

* types: update typings for ESM

* docs: fix typo

* test: set typescript to ES2020 mode

* test(types): add test cases for run callback with optional params

* test(types): test and fix async transformer typing

index.js

@@ -127,7 +127,7 @@ function base() {
   }
 
   // Data management.
-  // Getter / setter for processor-specific informtion.
+  // Getter / setter for processor-specific information.
   function data(key, value) {
     if (typeof key === 'string') {
       // Set `key`.

package.json

@@ -65,8 +65,8 @@
     "format": "remark . -qfo && prettier . -w --loglevel warn && xo --fix",
     "test-api": "node --unhandled-rejections=strict --conditions development test/index.js",
     "test-coverage": "c8 --check-coverage --branches 100 --functions 100 --lines 100 --statements 100 --reporter lcov node --unhandled-rejections=strict --conditions development test/index.js",
-    "xxx-test-types": "dtslint types",
-    "test": "npm run format && npm run test-coverage"
+    "test-types": "dtslint types",
+    "test": "npm run format && npm run test-coverage && npm run test-types"
   },
   "prettier": {
     "tabWidth": 2,