Remove the line in the development README about having a GHE account
Remove the line in the development README about having a GHE account

- Puppet (this repo) is now public on normal GitHub, so people won't
  need a GHE account to get started with the dev VM.
alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet