updated documentation

Author: marcosdiez

docs/guide/targetgroupbinding/targetgroupbinding.md

@@ -17,7 +17,10 @@ TargetGroupBinding CR supports TargetGroups of either `instance` or `ip` TargetT
     If TargetType is not explicitly specified, a mutating webhook will automatically call AWS API to find the TargetType for your TargetGroup and set it to correct value.
 
 ## Choosing the Target Group
-One can either use ``targetGroupARN`` of ``targetGroupName`` to identify a Target Group. Since there can be more than one Target Group with the same name, if you plan to use ``targetGroupName``, you are responsible to guarantee that there is only one Target Group with the aforemantioned name. Currently, the name is scanned whenever the ``TargetGroupBinding`` is created. So if a Target Group is created after a ``TargetGroupBinding`` is created, nothing happens. This may change in the future. AWS does not currently allow Target Group names to be changed, therefore the AWS Load Balancer Controller does not expect a name to change either.
+One can either use ``targetGroupARN`` of ``targetGroupName`` to identify a Target Group. Although both are unique and immutable in an AWS region, one only has control of the ``targetGroupName``, for ``targetGroupARN`` is generated by AWS and contain random characters.
+
+If you provide both ``targetGroupARN`` and ``targetGroupName``, beware that ``targetGroupARN`` prevails.
+
 
 ## Sample YAMLs
 ```yaml