Clarifies systemd docs and path

The path was a generic one, so this uses the default of the ansible-pulp
installer to align them more closely. It also updates the location of
the systemd unit files.

https://pulp.plan.io/issues/4615
closes #4615

docs/installation/instructions.rst

@@ -138,10 +138,15 @@ After installing and configuring Redis, you should configure it to start at boot
 Systemd
 -------
 
-To run the Pulp services, three systemd files needs to be created in /etc/systemd/system/. You can
-apply custom configuration here using the ``Environment`` option using settings from the
+To run the Pulp services, two systemd files needs to be created in /usr/lib/systemd/system/. You
+can apply custom configuration here using the ``Environment`` option using settings from the
 :ref:`Pulp settings documentation <configuration>`.
 
+.. note::
+
+    These examples may need their ``User`` updated and the path to the rq binary in ``ExecStart``.
+
+
 ``pulp-resource-manager.service``::
 
     [Unit]
@@ -154,7 +159,7 @@ apply custom configuration here using the ``Environment`` option using settings
     User=pulp
     WorkingDirectory=/var/run/pulp-resource-manager/
     RuntimeDirectory=pulp-resource-manager
-    ExecStart=/path/to/python/bin/rq worker -n resource-manager@%%h\
+    ExecStart=/usr/local/lib/pulp/bin/rq worker -n resource-manager@%%h\
               -w 'pulpcore.tasking.worker.PulpWorker'\
               -c 'pulpcore.rqconfig'\
               --pid=/var/run/pulp-resource-manager/resource-manager.pid
@@ -175,7 +180,7 @@ apply custom configuration here using the ``Environment`` option using settings
     User=pulp
     WorkingDirectory=/var/run/pulp-worker-%i/
     RuntimeDirectory=pulp-worker-%i
-    ExecStart=/path/to/python/bin/rq worker -w 'pulpcore.tasking.worker.PulpWorker'\
+    ExecStart=/usr/local/lib/pulp/bin/rq worker -w 'pulpcore.tasking.worker.PulpWorker'\
               -n reserved-resource-worker-%i@%%h\
               -c 'pulpcore.rqconfig'\
               --pid=/var/run/pulp-worker-%i/reserved-resource-worker-%i.pid