Bug#926361: Mention --width in paragraph

[積丹尼 Dan Jacobson]

Package: procps
Version: 2:3.3.15-2
File: /usr/share/man/man1/ps.1.gz
Severity: minor

   --cols option may be used to exactly determine the width in this case.  The 
w or -w option may be also be
   used to adjust width.

Also mention --width in that sentence.

And mention if --width is the same as --columns and COLUMNS variable.