Add heroku scaling commands to publication process

Why are these changes being introduced:

* the preservation job uses a lot of memory. Scaling the worker job
  where preservation is done to a dyno with additional memory will help
  give us a bit more headroom

Relevant ticket(s):

* https://mitlibraries.atlassian.net/browse/ETD-598

How does this address that need:

* provides instructions on how and why to scale the worker dyno before
  and after processing the output queue for publishing jobs

Document any side effects to this change:

* This doesn't really solve the problem, but masks it for our common
  thesis sizes. To fully address this problem we'll need to revisit
  how we create the preservation zip files

README.md

@@ -365,14 +365,21 @@ Publication Review - Publish)
   [DSS repo](https://github.com/MITLibraries/dspace-submission-service#run-stage))
 4. ETD processes output queue to update records and send email to stakeholders with summary data and list
   of any error records. As of now this is a manual process, but can be triggered via rake task using the following
-  Heroku run command:
+  sequence of heroku-cli commands:
 
   ```shell
+  # scale the worker dyno to ensure we have enough memory
+  heroku ps:scale worker=1:standard-2x --app TARGET-HEROKU-APP
+
+  # run the output queue processing job
   heroku run -s standard-2x rails dss:process_output_queue --app TARGET-HEROKU-APP
+
+  # wait for all ETD emails to be received (the preservation email is the final one to look for)
+  # scale the worker back down so we do not pay for more CPU/memory than we need
+  heroku ps:scale worker=1:standard-1x --app TARGET-HEROKU-APP
   ```
 
-Note the `-s` option, which sets the dyno size for the run command. We are scaling to the larger '2X' dyno because
-this job is very memory-intensive.
+Note the `-s` option on the second command, which sets the dyno size for the run command. We are scaling to the larger '2X' dyno because this job is very memory-intensive. We also first scale the worker dyno to 2x and then set it back to 1x when we are done for the same reason (preservation takes a lot of memory).
 
 ### Publishing a single thesis