Update the Cloud KMS documentation to link to the main site
Update the Cloud KMS documentation to link to the main site

This avoids duplicating a lot of samples within our page.

jskeet/google-cloud-dotnet,jskeet/google-cloud-dotnet,jskeet/google-cloud-dotnet,jskeet/google-cloud-dotnet,googleapis/google-cloud-dotnet,jskeet/gcloud-dotnet,jskeet/google-cloud-dotnet,googleapis/google-cloud-dotnet,googleapis/google-cloud-dotnet