Documentation/admin-guide: kernel-parameters: hyphenate comma-separated

Hyphenate "comma separated" when it is used as a compound adjective.
hyphenated.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20210101040831.4148-1-rdunlap@infradead.org


Signed-off-by: Jonathan Corbet <corbet@lwn.net>