Sorry for the confusion! Help docs are in Settings > Help.
This is kind of a sticking point for me, because one app after another has gotten this wrong (see Ulysses' bizarro link editing, for example), and I'm just not going to use an app if it wants to make me convert all my files to a proprietary version of the syntax.
Is it not working for you?
It looks like when I add the angle brackets that CommonMark allows to circumvent the spaces thing, some variations still don't work: https://i.imgur.com/nqiQnl3.png
For one more note, the obsidian.css thing for styling is deeply unintuitive, because you can't edit it from inside the app: if you make a note named "obsidian.css" at the root level, that gets ignored because it's actually obsidian.css.md, so you can only edit the styling with a separate app altogether to create/edit that file directly.
Also, on Mac it should be under the actual Help menu, the same way that there should be an Obsidian -> Preferences... menu item (hotkey cmd+,) to open settings. Conventions are important!
Ideally the help docs can be opened as its own vault and can be a nice testing ground for a new user to play around with the functionality.