docs/aws: Document initial_lifecycle_hook in aws_autoscaling_group

This is a useful feature that seems to have been added in September,
with 7dd7078, but has not yet been documented.

website/source/docs/providers/aws/r/autoscaling_group.html.markdown

@@ -30,11 +30,28 @@ resource "aws_autoscaling_group" "bar" {
   placement_group           = "${aws_placement_group.test.id}"
   launch_configuration      = "${aws_launch_configuration.foobar.name}"
 
+  initial_lifecycle_hook {
+    name                   = "foobar"
+    default_result         = "CONTINUE"
+    heartbeat_timeout      = 2000
+    lifecycle_transition   = "autoscaling:EC2_INSTANCE_LAUNCHING"
+
+    notification_metadata = <<EOF
+{
+  "foo": "bar"
+}
+EOF
+
+    notification_target_arn = "arn:aws:sqs:us-east-1:444455556666:queue1*"
+    role_arn                = "arn:aws:iam::123456789012:role/S3Access"
+  }
+
   tag {
     key                 = "foo"
     value               = "bar"
     propagate_at_launch = true
   }
+
   tag {
     key                 = "lorem"
     value               = "ipsum"
@@ -54,6 +71,12 @@ The following arguments are supported:
 * `availability_zones` - (Optional) A list of AZs to launch resources in.
    Required only if you do not specify any `vpc_zone_identifier`
 * `launch_configuration` - (Required) The name of the launch configuration to use.
+* `initial_lifecycle_hook` - (Optional) One or more
+  [Lifecycle Hooks](http://docs.aws.amazon.com/autoscaling/latest/userguide/lifecycle-hooks.html)
+  to attach to the autoscaling group **before** instances are launched. The
+  syntax is exactly the same as the separate
+  [`aws_autoscaling_lifecycle_hook`](/docs/providers/aws/r/autoscaling_lifecycle_hooks.html)
+  resource, without the `autoscaling_group_name` attribute.
 * `health_check_grace_period` - (Optional, Default: 300) Time (in seconds) after instance comes into service before checking health.
 * `health_check_type` - (Optional) "EC2" or "ELB". Controls how health checking is done.
 * `desired_capacity` - (Optional) The number of Amazon EC2 instances that
@@ -120,7 +143,18 @@ The following attributes are exported:
 * `target_group_arns` (Optional) list of Target Group ARNs that apply to this
 AutoScaling Group
 
-~> **NOTE:** When using `ELB` as the health_check_type, `health_check_grace_period` is required.
+~> **NOTE:** When using `ELB` as the `health_check_type`, `health_check_grace_period` is required.
+
+~> **NOTE:** Terraform has two types of ways you can add lifecycle hooks - via
+the `initial_lifecycle_hook` attribute from this resource, or via the separate
+[`aws_autoscaling_lifecycle_hook`](/docs/providers/aws/r/autoscaling_lifecycle_hooks.html)
+resource. `initial_lifecycle_hook` exists here because any lifecycle hooks
+added with `aws_autoscaling_lifecycle_hook` will not be added until the
+autoscaling group has been created, and depending on your
+[capacity](#waiting-for-capacity) settings, after the initial instances have
+been launched, creating unintended behavior. If you need hooks to run on all
+instances, add them with `initial_lifecycle_hook` here, but take
+care to not duplicate these hooks in `aws_autoscaling_lifecycle_hook`.
 
 ## Waiting for Capacity
 

website/source/docs/providers/aws/r/autoscaling_lifecycle_hooks.html.markdown

@@ -10,6 +10,18 @@ description: |-
 
 Provides an AutoScaling Lifecycle Hook resource.
 
+~> **NOTE:** Terraform has two types of ways you can add lifecycle hooks - via
+the `initial_lifecycle_hook` attribute from the 
+[`aws_autoscaling_group`](/docs/providers/aws/r/autoscaling_group.html)
+resource, or via this one. Hooks added via this resource will not be added
+until the autoscaling group has been created, and depending on your
+[capacity](/docs/providers/aws/r/autoscaling_group.html#waiting-for-capacity)
+settings, after the initial instances have been launched, creating unintended
+behavior. If you need hooks to run on all instances, add them with
+`initial_lifecycle_hook` in
+[`aws_autoscaling_group`](/docs/providers/aws/r/autoscaling_group.html),
+but take care to not duplicate those hooks with this resource.
+
 ## Example Usage
 
 ```