add warning about base64 encoding on WSL

discussion here: https://discord.com/channels/686873244791210014/1308477897224229026/1308723749830524999

it seems the encoding works differently on WSL, so I built this tool which allows them to encode it via node https://stackblitz.com/edit/stackblitz-starters-fvhlsc?file=index.js&view=editor