Add more info about time.Duration and clearer deprecation notice

README.md

@@ -232,8 +232,8 @@ ASG Roller takes its configuration via environment variables. All environment va
 * `ROLLER_DRAIN_FORCE` [`bool` default: `true`]: If drain will force delete kubernetes resources if they violate PDB or grace periods.
 * `ROLLER_IGNORE_DAEMONSETS` [`bool`, default: `true`]: If set to `false`, will not reclaim a node until there are no DaemonSets running on the node; if set to `true` (default), will reclaim node when all regular pods are drained off, but will ignore the presence of DaemonSets, which should be present on every node anyways. Normally, you want this set to `true`.
 * `ROLLER_DELETE_LOCAL_DATA` [`bool`, default: `false`]: If set to `false` (default), will not reclaim a node until there are no pods with [emptyDir](https://kubernetes.io/docs/concepts/storage/volumes/#emptydir) running on the node; if set to `true`, will continue to terminate the pod and delete the local data before reclaiming the node. The default is `false` to maintain backward compatibility.
-* `ROLLER_INTERVAL` [`time.Duration`, default: `30s`]: Time between roller runs. Takes time duration such as 10s, 10m, 10d
-* `ROLLER_CHECK_DELAY` [`int`]: Time, in seconds, between checks of ASG status. deprecated, use `ROLLER_INTERVAL`.
+* `ROLLER_INTERVAL` [`time.Duration`, default: `30s`]: Time between roller runs. Decimal number with a unit suffix, such as "10s", "10m", "10d", "300ms", "-1.5h" or "2h45m". Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h". Internally uses [time.ParseDuration](https://golang.org/pkg/time/#ParseDuration)
+* `ROLLER_CHECK_DELAY` [`int`]: Time, in seconds, between checks of ASG status. **Deprecated**, use `ROLLER_INTERVAL`. If both `ROLLER_CHECK_DELAY` and `ROLLER_INTERVAL` are specified then `ROLLER_INTERVAL` is used.
 * `ROLLER_CAN_INCREASE_MAX` `bool`: If set to `true`, will increase the ASG maximum size to accommodate the increase in desired count. If set to `false`, will instead error when desired is higher than max.
 * `ROLLER_ORIGINAL_DESIRED_ON_TAG` [`bool`, default: `false`]: If set to `true`, will store the original desired value of the ASG as a tag on the ASG, with the key `aws-asg-roller/OriginalDesired`. This helps maintain state in the situation where the process terminates.
 * `ROLLER_VERBOSE` [`bool`, default: `false`]: If set to `true`, will increase verbosity of logs.