Add Google's 'no image preview' meta tag to organisation pages

Google sometimes displays organisation pages as a 'rich snippet'. Google decides what image they feature on these search results. As we do not control what image they use, and sometimes the wrong image may be problematic, we can prevent Google showing a preview image on these pages."

app/views/organisations/_meta.html.erb

@@ -2,6 +2,7 @@
 
 <% content_for :meta_tags do %>
   <%= tag("meta", name: "description", content: organisation.description) if organisation.description %>
+  <%= tag("meta", name: "robots", content: "max-image-preview:none") %>
   <%= auto_discovery_link_tag(:json, api_organisation_url(organisation.slug), title: organisation.title) %>
   <%= auto_discovery_link_tag(:atom, feed_organisation_url(organisation.slug, format: :atom), title: organisation.title) %>
 <% end %>

spec/features/organisation_spec.rb

@@ -58,14 +58,15 @@
     expect(page).to have_css(".content")
   end
 
-  it "includes description and autodiscovery meta tags" do
+  it "includes description, autodiscovery, and google no image preview meta tags" do
     visit "/government/organisations/prime-ministers-office-10-downing-street"
     padded_string =
       "10 Downing Street is the official residence and the office of the British Prime Minister.\
       The office helps the Prime Minister to establish and deliver the government’s overall strategy and policy priorities,\
       and to communicate the government’s policies to Parliament, the public and international audiences."
     string = padded_string.gsub("      ", " ")
     expect(page).to have_selector("meta[name='description'][content='#{string}']", visible: :hidden)
+    expect(page).to have_selector("meta[name='robots'][content='max-image-preview:none']", visible: :hidden)
     expect(page).to have_css("link[rel='alternate'][type='application/json'][href$='/api/organisations/prime-ministers-office-10-downing-street']", visible: :hidden)
     expect(page).to have_css("link[rel='alternate'][type='application/atom+xml'][href$='/government/organisations/prime-ministers-office-10-downing-street.atom']", visible: :hidden)
   end