Fix broken link to expenses-demo (#7492)
Fix broken link to expenses-demo (#7492)


tseaver/google-cloud-python,tswast/google-cloud-python,googleapis/google-cloud-python,tseaver/google-cloud-python,googleapis/google-cloud-python,tswast/google-cloud-python,tseaver/google-cloud-python,tswast/google-cloud-python,GoogleCloudPlatform/gcloud-python,GoogleCloudPlatform/gcloud-python