Add instructions for using rvm::rvmrc class
Add instructions for using rvm::rvmrc class

The instructions for using `file {‘/etc/rvmrc’: …}` would lead to a
duplicate attempt to edit said file as this module edits that file too.
holstvoogd/puppet-rvm,jangrewe/puppet-rvm,srclab/puppet-rvm,mklette/puppet-rvm,mklette/puppet-rvm,squarit/puppet-rvm,ajmaidak/puppet-rvm,jangrewe/puppet-rvm,squarit/puppet-rvm,maestrodev/puppet-rvm,skyscrapers/puppet-rvm,skyscrapers/puppet-rvm,maestrodev/puppet-rvm,Adaptavist/puppet-rvm,Adaptavist/puppet-rvm,srclab/puppet-rvm,holstvoogd/puppet-rvm