Describe the feature or problem you’d like to solve

My merged PR #8342 formatted all special phrases like commands (gh help issue), flags (--json), and special values (true) with backticks (`), which represented a web-first direction.

But as #8348 briefly mentioned, users might be more used to double-quotes instead of back-quotes when reading on terminal, for instance in manpages, gh help <subcommand> output, and perhaps also shell completions.

Proposed solution

Stick to backquote on web, but use double-quotes for terminal material.

Additional context

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