Expand zpool-remove.8 manpage with example results

[smokris]

Motivation and Context

In the zpool-remove manpage's example of removing mirrors, it wasn't clear to me whether the removal commands would remove the entire vdev, or merely cause the mirrored vdev become unmirrored (reduce its redundancy). I performed a test and confirmed that it's the former, so I figured it might be useful to include the results in the example.

Also, zpool-remove.8 has a comment cross-referencing to zpool.8, but the example number was off, so I fixed it.

How Has This Been Tested?

Verified formatting by running:

man ./man/man8/zpool-remove.8
man ./man/man8/zpool.8

Also ran:

./scripts/mancheck.sh man

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
  • I didn't find a style guide for manpages.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
  • n/a
• I have run the ZFS Test Suite with this change applied.
  • n/a
• All commit messages are properly formatted and contain Signed-off-by.

[amotin]

Looks good to me, but makes me wonder why are we duplicating the examples.