use correct datatype for port param in README.md
use correct datatype for port param in README.md

fatmcgav/puppetlabs-rabbitmq,voxpupuli/puppet-rabbitmq,Slm0n87/puppet-rabbitmq,puppetlabs/puppetlabs-rabbitmq,Slm0n87/puppet-rabbitmq,voxpupuli/puppet-rabbitmq,puppetlabs/puppetlabs-rabbitmq,fuel-infra/puppetlabs-rabbitmq,Slm0n87/puppet-rabbitmq,fuel-infra/puppetlabs-rabbitmq,fatmcgav/puppetlabs-rabbitmq