fix some typos and clarify domain verification requirement [REVIEW]

README.md

@@ -17,3 +17,11 @@ For Google APIs and these credentials should correspond to a user with owner or
 editor access to the target project. You can use the ``gcloud`` command line
 tool to set your personal credentials as application default credentials. See
 the ``gcloud auth application-default`` command output for more information.
+
+## Custom domain mapping
+
+Setting the `dns_name` will create a domain mapping for the webapp. Before
+setting this value you *must* have verified ownership of the domain with Google.
+[Instructions on how to do
+this](https://guidebook.devops.uis.cam.ac.uk/en/latest/notes/google-domain-verification/)
+can be found in the DevOps division guidebook.

main.tf

@@ -109,7 +109,7 @@ resource "google_cloud_run_service_iam_member" "webapp_all_users_invoker" {
 
 # Domain mapping for default web-application. Only present if the domain is
 # verified. We use the custom DNS name of the webapp if provided but otherwise
-# the webapp is hosted at [SERVICEN NAME].[PROJECT DNS ZONE]. We can't create
+# the webapp is hosted at [SERVICE NAME].[PROJECT DNS ZONE]. We can't create
 # the domain mapping if the domain is *not* verified because Google won't let
 # us.
 resource "google_cloud_run_domain_mapping" "webapp" {

variables.tf

@@ -61,7 +61,7 @@ variable "dns_name" {
   description = <<EOI
 If non-empty, a domain mapping will be created for the webapp from this domain
 to point to the webapp. The domain must first have been verified by Google and
-the account being used by the google provider nust have been added as an owner.
+the account being used by the google provider must have been added as an owner.
 
 If and only if a domain mapping has been created, the
 "domain_mapping_resource_record" output will be a non-empty map and the