Documentation: sysrq: convert to third person

Documentation: sysrq: convert to third person

Two parts of the sysrq documentation have sentences written from a first
person's point of view.

Documentation is generally written from a third person's view in a
formal way.

Convert those senteces to be less personal and generic.

Signed-off-by: Cengiz Can <cengiz@kernel.wtf>
Link: https://lore.kernel.org/r/20210629141508.52229-1-cengiz@kernel.wtf
Signed-off-by: Jonathan Corbet <corbet@lwn.net>