Remove section about Pact Broker basic auth
Remove section about Pact Broker basic auth

Basic auth is mentioned in the README for the app [^1]. We should
have a separate, more detailed manual if we want to describe how
the Pact testing is orchestrated in Jenkins - this wasn't useful.

[^1]: https://github.com/alphagov/govuk-pact-broker#set-up-environment-variables-for-credentials

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