website: document how to enable advanced networking

website/source/docs/builders/amazon-chroot.html.md

@@ -125,8 +125,11 @@ each category, the available configuration keys are alphabetized.
     forces Packer to find an open device automatically.
 
 - `enhanced_networking` (boolean) - Enable enhanced
-    networking (SriovNetSupport and ENA) on HVM-compatible AMIs. If true, add
-    `ec2:ModifyInstanceAttribute` to your AWS IAM policy.
+  networking (SriovNetSupport and ENA) on HVM-compatible AMIs. If true, add
+  `ec2:ModifyInstanceAttribute` to your AWS IAM policy. Note: you must make
+  sure enhanced networking is enabled on your instance. See [Amazon's
+  documentation on enabling enhanced networking](
+  https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/enhanced-networking.html#enabling_enhanced_networking)
 
 - `force_deregister` (boolean) - Force Packer to first deregister an existing
     AMI if one with the same name already exists. Default `false`.

website/source/docs/builders/amazon-ebs.html.md

@@ -163,7 +163,10 @@ builder.
 
 - `enhanced_networking` (boolean) - Enable enhanced
   networking (SriovNetSupport and ENA) on HVM-compatible AMIs. If true, add
-  `ec2:ModifyInstanceAttribute` to your AWS IAM policy.
+  `ec2:ModifyInstanceAttribute` to your AWS IAM policy. Note: you must make
+  sure enhanced networking is enabled on your instance. See [Amazon's
+  documentation on enabling enhanced networking](
+  https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/enhanced-networking.html#enabling_enhanced_networking)
 
 - `force_deregister` (boolean) - Force Packer to first deregister an existing
   AMI if one with the same name already exists. Default `false`.

website/source/docs/builders/amazon-ebssurrogate.html.md

@@ -155,8 +155,11 @@ builder.
     Default `false`.
 
 - `enhanced_networking` (boolean) - Enable enhanced
-    networking (SriovNetSupport) on HVM-compatible AMIs. If true, add
-    `ec2:ModifyInstanceAttribute` to your AWS IAM policy.
+  networking (SriovNetSupport and ENA) on HVM-compatible AMIs. If true, add
+  `ec2:ModifyInstanceAttribute` to your AWS IAM policy. Note: you must make
+  sure enhanced networking is enabled on your instance. See [Amazon's
+  documentation on enabling enhanced networking](
+  https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/enhanced-networking.html#enabling_enhanced_networking)
 
 - `force_deregister` (boolean) - Force Packer to first deregister an existing
     AMI if one with the same name already exists. Default `false`.

website/source/docs/builders/amazon-ebsvolume.html.md

@@ -101,8 +101,11 @@ builder.
     Default `false`.
 
 - `enhanced_networking` (boolean) - Enable enhanced
-    networking (SriovNetSupport and ENA) on HVM-compatible AMIs. If true, add
-    `ec2:ModifyInstanceAttribute` to your AWS IAM policy.
+  networking (SriovNetSupport and ENA) on HVM-compatible AMIs. If true, add
+  `ec2:ModifyInstanceAttribute` to your AWS IAM policy. Note: you must make
+  sure enhanced networking is enabled on your instance. See [Amazon's
+  documentation on enabling enhanced networking](
+  https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/enhanced-networking.html#enabling_enhanced_networking)
 
 - `iam_instance_profile` (string) - The name of an [IAM instance
     profile](https://docs.aws.amazon.com/IAM/latest/UserGuide/instance-profiles.html)

website/source/docs/builders/amazon-instance.html.md

@@ -186,8 +186,11 @@ builder.
     Default `false`.
 
 - `enhanced_networking` (boolean) - Enable enhanced
-    networking (SriovNetSupport and ENA) on HVM-compatible AMIs. If true, add
-    `ec2:ModifyInstanceAttribute` to your AWS IAM policy.
+  networking (SriovNetSupport and ENA) on HVM-compatible AMIs. If true, add
+  `ec2:ModifyInstanceAttribute` to your AWS IAM policy. Note: you must make
+  sure enhanced networking is enabled on your instance. See [Amazon's
+  documentation on enabling enhanced networking](
+  https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/enhanced-networking.html#enabling_enhanced_networking)
 
 - `force_deregister` (boolean) - Force Packer to first deregister an existing
     AMI if one with the same name already exists. Defaults to `false`.