* docs: updated ws's readme to include optional packages
- added optional packages to the README.md
- added an example on how to add a listener to the ws manager, in the README.md
* docs: changed "addEventListener" to "on" in ws's readme
changed "addEventListener" to "on" in @discord.js/ws README.md
Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>