Add rdoc about objects can't Marshal#dump. [ruby-core:23314]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@25650 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Add rdoc about objects can't Marshal#dump. [ruby-core:23314]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@25650 b2dd03c8-39d4-4d8f-98ff-823fe69b080e