Add to configuration server_processes_manager module

[GeorgeMurad]

Testing instructions (if applicable)

1. Go to the server processes manager without setting up LORIS-MRI code path /opt/Loris-MRI/bin/mri/ in the configuration module.
2. See that page doesn't load.
3. See that this is not mentioned in the README or TestPlan.

Link(s) to related issue(s):

• [server_processes_manager] Documentation out of date #9153