Document and sign-post additional systemd resource control options.

The systemd administrator may wish to use additional resource control
facilities which systemd provides. Document the existence of these, and
provide some example options in commented form.

examples/systemd/rest-server.service

@@ -55,5 +55,19 @@ RestrictRealtime=true
 SystemCallArchitectures=native
 SystemCallFilter=@system-service
 
+# Additionally, you may wish to use some of the systemd options documented in
+# systemd.resource-control(5) to limit the CPU, memory, file-system I/O and
+# network I/O that the rest-server is permitted to consume according to the
+# individual requirements of your installation.
+#CPUQuota=25%
+#MemoryMax=bytes
+#MemorySwapMax=bytes
+#TasksMax=N
+#IOReadBandwidthMax=device bytes
+#IOWriteBandwidthMax=device bytes
+#IOReadIOPSMax=device IOPS, IOWriteIOPSMax=device IOPS
+#IPAccounting=true
+#IPAddressAllow=
+
 [Install]
 WantedBy=multi-user.target