Remove section `Testing whether a version of Ruby is in use`
Remove section `Testing whether a version of Ruby is in use`

This section showed how to check for a version of ruby, but using
Fabric, which is deprecated.

Best thing now would be to get into the machines and check manually.

alphagov/govuk-developer-docs,alphagov/govuk-developer-docs,alphagov/govuk-developer-docs,alphagov/govuk-developer-docs