Bug: some OS tabs combine Unix/MacOS, some separate them

[nedbat]

Describe the bug

Is there a reason we sometimes use three tabs (Linux and Mac separate) and sometimes use two ("Unix/MacOS" as one tab)?

Screenshots

No response

Additional context

No response

[hugovk]

Sometimes Unix/macOS contain the same instructions, so it's to avoid duplicating them in the .rst (and to save the reader from clicking each tab to compare things that are the same).