Add link to this repo on the website

[Yiyiyimu]

Maybe we could add a link to the website to guide users contributing (or just star), or people even might not know it's opensource 🤣

[Baoyuantop]

Maybe we can add a Github logo link on this page of API7.

[LiteSun]

Maybe we can add a Github logo link on this page of API7(contributor-graph page).

agree, it would be very useful to introduce our repo! what do you think? cc @juzhiyuan