Add cross-project IAM binding support (#955)

* Add recipe for cross-project IAM permissions

Add cross-project IAM permission support for the following resources:
storage buckets
projects
organizations
folders

docs/tfengine/schemas/iam_members.md

@@ -7,7 +7,3 @@
 | Property | Description | Type | Required | Default | Pattern |
 | -------- | ----------- | ---- | -------- | ------- | ------- |
 | iam_members | [Module](https://github.com/terraform-google-modules/terraform-google-iam) | object | false | - | - |
-| iam_members.*pattern* | - | array(object) | false | - | ^storage_bucket\|project\|organization\|folder$ |
-| iam_members.*pattern*.bindings | Map of IAM role to list of members to grant access to the role. | object | false | - | - |
-| iam_members.*pattern*.bindings.*pattern* | - | array(string) | false | - | .+ |
-| iam_members.*pattern*.resource_ids | ID of resources to assign the bindings.<br><br>Should be the following for each resource type:                    project: project IDs. e.g. [example_project_id]                    storage_bucket : storage bucket names. e.g. [example_bucket_one, example_bucket_two]                    folder: folder IDs. e.g. [12345678]                    organization: organizations IDs. e.g [12345678] | array(string) | false | - | - |