fix mandoc warnings

- sort references in SEE ALSO section to section number, name.
- cols.1: proper order of sections.
- wrap lines to max 79 column length.

nl.1

@@ -14,8 +14,9 @@
 .Nm
 reads lines from the named
 .Ar file
-and writes them to stdout with non-empty lines
-numbered.  If no file is given
+and writes them to stdout with non-empty lines numbered. If no
+.Ar file
+is given
 .Nm
 reads from stdin.
 .Sh OPTIONS
@@ -38,7 +39,7 @@ a regular expression as defined in
 .It Fl i Ar incr
 Defines the increment between numbered lines.
 .It Fl s Ar sep
-Defines the string used to separate line numbers and lines.  By default this is
+Defines the string used to separate line numbers and lines. By default this is
 a tab.
 .El
 .Sh SEE ALSO