update storage README to reflect recommended practices
# Azure Storage SDK for Go (Preview)
-The `github.com/Azure/azure-sdk-for-go/storage` package is used to perform REST operations against the [Azure Storage Service](https://docs.microsoft.com/en-us/azure/storage/). To manage your storage accounts (Azure Resource Manager / ARM), use the [github.com/Azure/azure-sdk-for-go/arm/storage](https://github.com/Azure/azure-sdk-for-go/tree/master/arm/storage) package. For your classic storage accounts (Azure Service Management / ASM), use [github.com/Azure/azure-sdk-for-go/services/classic/management/storageservice](https://github.com/Azure/azure-sdk-for-go/tree/master/management/storageservice) package.
+:exclamation: IMPORTANT: This package is in maintenance only and will be deprecated in the
+future. Consider using the new package for blobs currently in preview at
+[github.com/Azure/azure-storage-blob-go](https://github.com/Azure/azure-storage-blob-go).
+New Table, Queue and File packages are also in development.
The `github.com/Azure/azure-sdk-for-go/storage` package is used to manage
[Azure Storage](https://docs.microsoft.com/en-us/azure/storage/) data plane
