[readme]: add description of ECMAScript

README.md

@@ -14,8 +14,13 @@ fanciful decoration.
 
 # example
 
+Example files: [example/parse.js](./example/parse.js) (CommonJS) / [example/parse.mjs](./example/parse.mjs) (ECMAScript)
+
 ``` js
-var argv = require('minimist')(process.argv.slice(2));
+const minimist = require('minimist'); // (for CommonJS)
+// import minimist from 'minimist'; // (for ECMAScript)
+
+const argv = minimist(process.argv.slice(2));
 console.log(argv);
 ```
 
@@ -42,10 +47,10 @@ $ node example/parse.js -x 3 -y 4 -n5 -abc --beep=boop --no-ding foo bar baz
 # methods
 
 ``` js
-var parseArgs = require('minimist')
+const parseArgs = require('minimist')
 ```
 
-## var argv = parseArgs(args, opts={})
+## const argv = parseArgs(args, opts={})
 
 Return an argument object `argv` populated with the array arguments from `args`.