* man/ruby.1, man/erb.1, man/goruby.1, man/irb.1:
  fix document title formatting and volume name,
  improve "REPORTING BUGS" section: fix mdoc formatting error
  (wrong macro for bullet list items), small rewordings.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58411 b2dd03c8-39d4-4d8f-98ff-823fe69b080e