Document `channels-auth-token-middlewares` third party package

[johnthagen]

channels-auth-token-middlewares fills an important role for providing authentication support out of the box for DRF applications using JWT authentication.

This question has been asked several times on SO:

• https://stackoverflow.com/questions/65297148
• https://stackoverflow.com/questions/43392889

Hopefully by promoting it in the community page, more users can discover it.

[johnthagen]

CC @YegorDB for awareness