Make Synapse not log to text files

Somewhat related to #213 (Github Pull Request).

We've been moving in the opposite direction for quite a long time.
All services should just leave logging to systemd's journald.

CHANGELOG.md

@@ -1,3 +1,22 @@
+# 2019-07-04
+
+## Synapse no longer logs to text files
+
+Following what the official Synapse Docker image is doing ([#5565](https://github.com/matrix-org/synapse/pull/5565)) and what we've been doing for mostly everything installed by this playbook, **Synapse no longer logs to text files** (`/matrix/synapse/run/homeserver.log*`).
+
+From now on, Synapse would only log to console, which goes to systemd's journald.
+To see Synapse's logs, execute: `journalctl -fu matrix-synapse`
+
+Because of this, the following variables have become obsolete and were removed:
+
+- `matrix_synapse_max_log_file_size_mb`
+- `matrix_synapse_max_log_files_count`
+
+To prevent confusion, it'd be better if you delete all old files manually after you've upgraded (`rm -f /matrix/synapse/run/homeserver.log*`).
+
+Because Synapse is incredibly chatty when it comes to logging (here's [one such issue](https://github.com/matrix-org/synapse/issues/4751) describing the problem), if you're running an ancient distribution (like CentOS 7.0), be advised that systemd's journald default logging restrictions may not be high enough to capture all log messages generated by Synapse. This is especially true if you've got a busy (Synapse) server. We advise that you manually add `RateLimitInterval=0` and `RateLimitBurst=0` under `[Storage]` in the `/etc/systemd/journald.conf` file, followed by restarting the logging service (`systemctl restart systemd-journald`).
+
+
 # 2019-06-27
 
 ## (BC Break) Discord bridge configuration is now entirely managed by the playbook