Modify systemd unit file reference to align with installation instruction (#6369)

Signed-off-by: Clifford Garwood II <cliff@cigii.com>

changelog.d/6369.doc

+Update documentation and variables in user contributed systemd reference file.

contrib/systemd/README.md

+# Setup Synapse with Systemd
+This is a setup for managing synapse with a user contributed systemd unit 
+file. It provides a `matrix-synapse` systemd unit file that should be tailored 
+to accommodate your installation in accordance with the installation 
+instructions provided in [installation instructions](../../INSTALL.md).
+
+## Setup
+1. Under the service section, ensure the `User` variable matches which user
+you installed synapse under and wish to run it as. 
+2. Under the service section, ensure the `WorkingDirectory` variable matches
+where you have installed synapse.
+3. Under the service section, ensure the `ExecStart` variable matches the
+appropriate locations of your installation.
+4. Copy the `matrix-synapse.service` to `/etc/systemd/system/`
+5. Start Synapse: `sudo systemctl start matrix-synapse`
+6. Verify Synapse is running: `sudo systemctl status matrix-synapse`
+7. *optional* Enable Synapse to start at system boot: `sudo systemctl enable matrix-synapse`

contrib/systemd/matrix-synapse.service

@@ -4,8 +4,11 @@
 #    systemctl enable matrix-synapse
 #    systemctl start matrix-synapse
 #
+# This assumes that Synapse has been installed by a user named
+# synapse.
+#
 # This assumes that Synapse has been installed in a virtualenv in
-# /opt/synapse/env.
+# the user's home directory: `/home/synapse/synapse/env`.
 #
 # **NOTE:** This is an example service file that may change in the future. If you
 # wish to use this please copy rather than symlink it.
@@ -23,7 +26,7 @@ User=synapse
 Group=nogroup
 
 WorkingDirectory=/opt/synapse
-ExecStart=/opt/synapse/env/bin/python -m synapse.app.homeserver --config-path=/opt/synapse/homeserver.yaml
+ExecStart=/home/synapse/synapse/env/bin/python -m synapse.app.homeserver --config-path=/home/synapse/synapse/homeserver.yaml
 SyslogIdentifier=matrix-synapse
 
 # adjust the cache factor if necessary