Document requirements for secrets generation etc

[tlienart]

(this may be done already)

• secrets need to be retrieved from Portal (format requirements: no newline)
• secrets are generated when setting up pool
• both secrets should be in /deploy and /task

[martintoreilly]

• SSH keys can be fetched using the get-ssh command (will be stored in private-pool-ssh-keys folder in the directory the az-vm-pool.py script is run from) [commit ab2f83e]
• SAS tokens can be fetched using the get-secrets command (will be stored in the secrets folder in the directory the az-vm-pool.py script is run from) [commit b54da7e]
• The secrets folder with SAS tokens and the az-queue.py and az-storage.py scripts an be copied to the deploy, setup and task subfolders of a specified pool directory using the init-directory command [commit b54da7e].

NOTE: The storage token will be automatically generated and uploaded when a pool is created or the refresh-sas command is run. For now the queue token must be the primary key of the RootManageSharedAccessKey of the Service Bus containing the queue. It must also be manually uploaded to the vmsecrets pool storage container if it is to be fetched to a new pool management computer using the get-secrets command. Note that the queue SAS key file must be named azure_vm_pool_<resource-group>_sas_servicebus_management.txt.