Add details about the telemetry data that gets sent (if enabled)

docs/configuring-playbook-telemetry.md

@@ -3,12 +3,42 @@
 By default, this playbook configures your Matrix homeserver to not send any telemetry data anywhere.
 
 The [matrix.org](https://matrix.org) team would really appreciate it if you could help the project out by reporting
-anonymized usage statistics from your homeserver. Only very basic aggregate
-data (e.g. number of users) will be reported, but it helps track the
+anonymized usage statistics from your homeserver. Only very [basic aggregate
+data](#usage-statistics-being-submitted) (e.g. number of users) will be reported, but it helps track the
 growth of the Matrix community, and helps to make Matrix a success.
 
+
+## Enabling Telemetry
+
 If you'd like to **help by enabling submission of anonymized usage statistics** for your homeserver, add this to your configuration file (`inventory/matrix.<your-domain>/vars.yml`):
 
 ```yaml
 matrix_synapse_report_stats: true
 ```
+
+
+## Usage statistics being submitted
+
+If statistics reporting is enabled, the information that gets submitted to the matrix.org team [according to the source code](https://github.com/matrix-org/synapse/blob/master/synapse/app/homeserver.py) is:
+
+- your homeserver's domain name
+
+- uptime of the homeserver program
+
+- [Python](https://www.python.org/) version powering your homeserver
+
+- total number of users on your home server (including bridged users)
+
+- total number of native Matrix users on your home server
+
+- total number of rooms on your homeserver
+
+- total number of daily active users on your homeserver
+
+- total number of daily active rooms on your homeserver
+
+- total number of messages sent per day
+
+- cache setting information
+
+- CPU and memory statistics for the homeserver program