Document example key server statistics

cmd/server/assets/realmadmin/_stats_keyserver.html

@@ -5,7 +5,9 @@ <h1>Key server stats</h1>
   The data below shows realm statistics and visualizations gathered from the key server.
 </p>
 
-{{if .keyServerOverride}}<p>Stats sourced from: "{{.keyServerOverride}}}</p>{{end}}
+{{if .keyServerOverride}}
+  <p>Stats sourced from: "{{.keyServerOverride}}}</p>
+{{end}}
 
 <div class="card shadow-sm mb-3">
   <div class="card-header">

docs/realm-admin-guide.md

@@ -15,6 +15,8 @@
 - [API keys](#api-keys)
 - [ENX redirector service](#enx-redirector-service)
 - [Mobile apps](#mobile-apps)
+- [Statistics](#statistics)
+  - [Key server statistics](#key-server-statistics)
 - [Rotating certificate signing keys](#rotating-certificate-signing-keys)
   - [Automatic Rotation](#automatic-rotation)
   - [Manual Rotation](#manual-rotation)
@@ -251,6 +253,40 @@ processes. You still must submit your application for inclusion in the Play
 Store and App Store respectively, separate from this system.
 
 
+## Statistics
+
+The verification server provides statistics for various facets of the system.
+Most statistics are also available [via the API](api.md).
+
+### Key server statistics
+
+Some statistics are automatically collected, while other  statistics require
+opt-in consent. The system automatically collects information about the number
+of codes issued, codes claimed, and error rates.
+
+You can optionally enable
+enhanced statistics collection from the corresponding key server. **Enabling these statistics may require an update to your application's privacy policy or data handling agreement.** If enabled, enhanced statistics include information such as:
+
+- Total number of TEKs published: the total number of TEKs that have been
+  published to the key server (per day).
+
+- Requests with revisions: the total number of uploads that contained at least one TEK revision.
+
+- Requests missing onset: the total number of uploads where no onset date was provided.
+
+- Requests by operating system: a breakdown of requests by target operating
+  system (Android and iPhone).
+
+- TEK age distribution: this shows a distribution of the ages of TEKs by how
+  many days old each TEK is.
+
+- Onset upload distribution: reflects the distribution of the time between the
+  TEK's symptom onset time and when the key was uploaded.
+
+Here is an example of the statistics page:
+
+![stats](images/admin/stats.png "Verification server stats")
+
 ## Rotating certificate signing keys
 
 Periodically, you will want to rotate the certificate signing key for your verification certificates.