* ext/openssl/lib/openssl/*.rb: [DOC] Document the following:

  - Integer#to_bn
  - OpenSSL::Buffering module
  - Document deprecated OpenSSL::Digest::Digest compatibility class
  - OpenSSL::Config

  These changes were based on a patch by @vbatts via GH-436
  https://github.com/ruby/ruby/pull/436


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43663 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
commit typo


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43664 b2dd03c8-39d4-4d8f-98ff-823fe69b080e