Add 2FA clarification

[tip2tail]

Like many, I now use Two Factor Authentication with Plex (2FA).

In order to login and get an API token from an application such as plex_dupefinder, you ned to know the "workaround" of adding your 2FA code at the end of the password. Source: https://unraid-guides.com/2021/01/31/how-to-connect-plex-to-apps-that-dont-support-two-factor-authentication-2fa/

I have created a PR for this - #60. This change will add clarification to README.md and to the prompts from config.py

[notmayo]

You can also use token and 2fa will not be an issue :)