I updated the notion exporter to modified my newer notion2md exporter

[echo724]

Hello,

I appreciated your web that used my notion2md. I updated few more features like downloading files, exporting subpages, and tables. I tried to use notion2md from my repo as submodule, but it was hard to use it, so I changed my code so that perfectly fit your web. I changed few file names and structure of the exporter. Could you check it? Thank you