Move properties, parameters, events, and concepts around manual sections

The pages moved as follows:
  zpool-features.{5 => 7}
  spl{-module-parameters.5 => .4}
  zfs{-module-parameters.5 => .4}
  zfs-events.5 => into zpool-events.8
  zfsconcepts.{8 => 7}
  zfsprops.{8 => 7}
  zpoolconcepts.{8 => 7}
  zpoolprops.{8 => 7}

Reviewed-by: Richard Laager <rlaager@wiktel.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Co-authored-by: Daniel Ebdrup Jensen <debdrup@FreeBSD.org>
Closes #12149
Closes #12212

man/man8/zfs-upgrade.8

@@ -77,7 +77,7 @@ systems running older versions of ZFS.
 .Pp
 In general, the file system version is independent of the pool version.
 See
-.Xr zpool-features 5
+.Xr zpool-features 7
 for information on features of ZFS storage pools.
 .Pp
 In some cases, the file system version and the pool version are interrelated and