A minor overhaul: added comments, split cmds in 2, changed synopsis.
A minor overhaul: added comments, split cmds in 2, changed synopsis.

Split commands into two groups: one with optional count and one with
required argument.  Changed synopsis line accordingly.

Added some hopefully-helpful comments based on experiments, knowing
that not all hardware works the same.

PR:             docs/84101
Approved by:    keramida
MFC after:      3 days

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