Improve tests and update man page for healing recv

Fix the manpage. The "SYNOPSIS" section is incorrectly formatted for
receive -c. I also took this opportunity to reword some parts and
fix a run-on sentence in the manpage.

Add large block testing for corrective recv. This adds a new test
that makes sure blocks generated using zfs send -L/--large-block
large-block send flag are able to be used for healing.

Since with unloaded key and errlog feature enabled corruption is not
shown in zpool status #13675 is fixed the zfs_receive_corrective.ksh
test no longer sets -o feature@head_errlog=disabled on pool creation
so that it can also test for regressions related to head_errlog feature.

Note that the zfs_receive_compressed_corrective.ksh and
zfs_receive_large_block_corrective.ksh tests are still creating pools
with -o feature@head_errlog=disabled.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alek Pinchuk <apinchuk@axcient.com>
Closes #14615