fix: update lesson to reflect changes in UI and in number of the repos

[honzajavorek]

Fixes https://github.com/apify/apify-docs/issues/981. When updating the text I found out the examples don't work anymore, so I updated them too. I also changed some bits of code and texts, hopefully for the better.

I only touched the first half of the lesson which deals with Facebook, I didn't dare to even look further not to make this PR even larger. This was supposed to be a small fix, but ended up as pretty much a rewrite. Unfortunately that's something which I suspect will be true for most of the issues labeled as Academy 😬

Asking @TC-MO to review the text, and guessing that @metalwarrior665 🤘 could be the best person to review the code examples.