Update example for module

[crystalfp]

Just a minor point. I tried the example from README and it complains as below because the project has "type" = "module". Adding a note to the example could be sufficient.

import { RingBuffer } from 'ring-buffer-ts';
         ^^^^^^^^^^
SyntaxError: Named export 'RingBuffer' not found. The requested module 'ring-buffer-ts' is a
CommonJS module, which may not support all module.exports as named exports.
CommonJS modules can always be imported via the default export, for example using:

import pkg from 'ring-buffer-ts';
const { RingBuffer } = pkg;

Thanks!
mario