Remove references to Fabric from "Try kicking the Nginx machines"
Remove references to Fabric from "Try kicking the Nginx machines"

[Trello](https://trello.com/c/AGdifoDb/250-remove-fabric-and-replace-references-in-docs)

We've removed fabric and must now provide an alternative in our docs.

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