Add new google_compute_regions (hashicorp#1603)

* Add new google_compute_regions

* Add docs

* correct doc

Author: Sébastien GLON

docs/d/google_compute_regions.html.markdown

@@ -0,0 +1,38 @@
+---
+layout: "google"
+page_title: "Google: google_compute_regions"
+sidebar_current: "docs-google-datasource-compute-regions"
+description: |-
+  Provides a list of available Google Compute regions
+---
+
+# google\_compute\_regions
+
+Provides access to available Google Compute regions for a given project.
+See more about [regions and regions](https://cloud.google.com/compute/docs/regions-zones/) in the upstream docs.
+
+```
+data "google_compute_regions" "available" {}
+
+resource "google_compute_subnetwork" "cluster" {
+  count = "${length(data.google_compute_regions.available.names)}"
+  name          = "my-network"
+  ip_cidr_range = "10.36.${count.index}.0/24"
+  network       = "my-network"
+  region        = "${data.google_compute_regions.available.names[count.index]}"
+}
+```
+
+## Argument Reference
+
+The following arguments are supported:
+
+* `project` (Optional) - Project from which to list available regions. Defaults to project declared in the provider.
+* `status` (Optional) - Allows to filter list of regions based on their current status. Status can be either `UP` or `DOWN`.
+  Defaults to no filtering (all available regions - both `UP` and `DOWN`).
+
+## Attributes Reference
+
+The following attribute is exported:
+
+* `names` - A list of regions available in the given project

google.erb

@@ -43,6 +43,9 @@
       <li<%= sidebar_current("docs-google-datasource-project") %>>
         <a href="/docs/providers/google/d/google_project.html">google_project</a>
       </li>
+      <li<%= sidebar_current("docs-google-datasource-compute-regions") %>>
+      <a href="/docs/providers/google/d/google_compute_regions.html">google_compute_regions</a>
+      </li>
       <li<%= sidebar_current("docs-google-datasource-compute-ssl-policy") %>>
         <a href="/docs/providers/google/d/datasource_compute_ssl_policy.html">google_compute_ssl_policy</a>
       </li>