Fixed document (and relevant example code) for consistency and for hiding the iCredit testing URL

Hi Mayank, Eri and/or Joachim,

Thank you for the handover and all your efforts for the official support of our Ruby SDK by Illumina!

Could you please also update the official doc at https://developer.basespace.illumina.com/docs/content/documentation/sdk-samples/ruby-sdk-overview

Cheers,
Toshiaki