📒 [docs]: Fix broken link in FAQ section

[hinokuro86]

So basicly in this url of the generated docs of fiber

https://docs.gofiber.io/extra/faq#which-template-engines-does-fiber-support

The link of Slim template engine also redirects to the pug documentation (the previous link).

Ps: Awesome framework, really enjoying it!

[welcome]

Thanks for opening your first issue here! 🎉 Be sure to follow the issue template! If you need help or want to chat with us, join us on Discord https://gofiber.io/discord