dashboard_path in ApplicationHelper
dashboard_path in ApplicationHelper

/docs in production was calling this method which only existed in the
buildkite/buildkite app that it was a submodule of.

Adding it here allows buildkite/docs to be run in isolation.

The error when this is missing only manifests when bk_logged_in=true
cookie is set (i.e. #probably_authenticated? is true)

buildkite/docs,buildkite/docs,buildkite/docs,buildkite/docs