Document Azure retry settings

[bentsherman]

The following settings control the retry policy that Nextflow uses when calling the Azure Batch API:

• Considerations re: how often a job status is checked (i.e Azure jobs being checked every 1 second).

azure {
  retryPolicy {
    delay = '500 ms'
    maxDelay = '60 s'
    maxAttempts = 10
    jitter = 0.25
  }
}