docs: sysctl/fs: remove references to super-max/-nr

These were removed in 2.4.7.8. Remove references to super-max and
super-nr in the sysctl documentation.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20220930102937.135841-5-steve@sk2.org


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