Add basicAuth in README.md

[Camille Louédoc-Eyriès]

There is a basicAuth option as shown in this example.

However, this option does not appear in the README.md.

Related issue: #76

I can open a PR if you'd like 😄

[Jani Anttonen]

Please, feel free! Couldn't really keep up to date without the help of the OS community :)