add giscus to mkdocs-material official document website

[Jackiexiao]

giscus is great!!! why not add giscus to https://squidfunk.github.io/mkdocs-material website?

[squidfunk]

We have added it in the Blog section.

[Jackiexiao]

ok, great, I wonder if there is a better hints to info user you need to login first to comment from the begining, instead of scroll to the end of page to find sign with github button

[squidfunk]

This is rendered by Giscus, so better ask the maintainers of Giscus 😊