Add initial version of maintenance and troubleshooting doc

docs/README.md

@@ -18,4 +18,6 @@
 
 - [Maintenance / upgrading PostgreSQL](maintenance-upgrading-postgres.md)
 
-- [Uninstalling](uninstalling.md)
+- [Maintenance and Troubleshooting](maintenance-and-troubleshooting.md)
+
+- [Uninstalling](uninstalling.md)

docs/maintenance-and-troubleshooting.md

@@ -0,0 +1,23 @@
+# Maintenance and Troubleshooting
+
+## How to see the current status of your services
+
+You can check the status of your services by using `systemctl status`. Example:
+```
+sudo systemctl status matrix-nginx-proxy
+
+● matrix-nginx-proxy.service - Matrix nginx proxy server
+   Loaded: loaded (/etc/systemd/system/matrix-nginx-proxy.service; enabled; vendor preset: enabled)
+   Active: active (running) since Wed 2018-11-14 19:38:35 UTC; 49min ago
+```
+
+You can see the logs by using journalctl. Example:
+```
+sudo journalctl -fu matrix-synapse
+```
+
+## Postgres
+
+You can access the Postgres command line interface using the script installed on your server at `/usr/local/bin/matrix-postgres-cli`.
+
+This playbook attempts to preserve the Postgres version it starts with. When you are ready to upgrade to a new Postgres version, read through the [guide for upgrading PostgreSQL](maintenance-upgrading-postgres.md).