mke2fs.8: use extents vs extent in the man page

We print "extents" for the feature, so we should document "extents" in
the mke2fs's man page, even though we accept both "extent" and
"extents".

Addresses-Sourceforge-Bug: #3559210

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
1 file changed