Remove Ns before puctuation

* man/erb.1, man/irb.1, man/ri.1, man/ruby.1: Remove Ns before
  puctuation.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@56256 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

Author: knu

man/ri.1

@@ -167,8 +167,7 @@ Searches user-wide documents here.
 .Sh REPORTING BUGS
 .Bl -bullet
 .Li Security vulnerabilities should be reported via an email to
-.Aq [email protected] Ns
-.Li .
+.Aq [email protected] .
 Reported problems will be published after being fixed.
 .Pp
 .Li And you can report other bugs and feature requests via the