Fixing several issues in docs

[Borda]

📚 Documentation

As we found in #1465 (comment)
Let's remove these todos one by one and fix all skipped issues in a particular PRs:

https://github.com/Lightning-AI/metrics/blob/606dc17759fa7398acc61cf2c4f17fb986db4465/pyproject.toml#L110-L116

If you are interested in giving a hand and helping us, could you create a draft PR as soon as you remove one skip and mention this issue in your PR so we can keep track of ongoing work... 🐰

Also, before you start, please see already finished or ongoing fixes so we avoid duplicating work... 🦦

When yo are done, run: pre-commit --all-files which shall pass all green 🟢

Thanks!