Add stats endpoint

app/controllers/api/v1/stats_controller.rb

@@ -0,0 +1,9 @@
+module Api::V1
+  class StatsController < BaseController
+    def index
+      @park_count = Park.count
+      @alert_count = Alert.count
+      @park_with_most_alerts = Alert.group(:park_code).count.max
+    end
+  end
+end

app/views/api/v1/stats/index.json.jbuilder

@@ -0,0 +1,6 @@
+json.park_count @park_count
+json.alert_count @alert_count
+json.most_alerts do
+  json.park_code @park_with_most_alerts[0]
+  json.alert_count @park_with_most_alerts[1]
+end