Show we have a list of "guides" inside Livebook itself

[hugobarauna]

I have seen people trying to find docs/guides about Livebook multiple times without knowing there's a Learn section inside Livebook that could answer some of their questions.

Although we plan to expand our docs at https://hexdocs.pm/livebook, in the meantime, maybe we can just add another entry to the main menu with a "Guides" title, something like that:

In that section, we could explain multiple guides inside the Livebook itself.

This would help people who go to the Livebook website looking for docs.

[jonatanklosko]

FWIW we actually mention the Learn section on the main page, but having a separate page that points to guides and docs doesn't hurt, yeah.

[josevalim]

Suggestion: make "Guides" link to "hexdocs.pm/livebook" and we change the README to mention the Learn section as early as possible?

[hugobarauna]

@josevalim Good idea. 👍