Update terraform files and instructions (#1402)

* Update terraform files and instructions

Update proxy terraform files based on current best practices and allow
exclusion of forwarding rules for HTTP endpoints.  Specifically:
-   Add a "public_web_whois" input to allow disabling the public HTTP
    whois forwarding.
-   Add "description" fields to all variables.
-   Move outputs of the top-level module into "outputs.tf".
-   Auto-reformat using hclfmt.

proxy/terraform/outputs.tf

@@ -0,0 +1,21 @@
+output "proxy_service_account" {
+  value       = module.proxy.proxy_service_account
+  description = "Service account the proxy runs under."
+}
+
+output "proxy_name_servers" {
+  value       = module.proxy.proxy_name_servers
+  description = "Name servers for the proxy's domain."
+}
+
+output "proxy_instance_groups" {
+  value       = module.proxy.proxy_instance_groups
+  description = <<EOF
+    The name of the GCE instance group backing up the proxy's cluster.
+    EOF
+}
+
+output "proxy_ip_addresses" {
+  value       = module.proxy.proxy_ip_addresses
+  description = "The proxy IP addresses."
+}