Fixing example in comments that raised an error by @JackDanger [fix GH-345]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41766 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/net/http.rb

@@ -671,7 +671,7 @@ module Net   #:nodoc:
     #
     # Sets an output stream for debugging.
     #
-    #   http = Net::HTTP.new
+    #   http = Net::HTTP.new(hostname)
     #   http.set_debug_output $stderr
     #   http.start { .... }
     #