Better document Passenger file to avoid surprises

app/passenger_wsgi.py

@@ -1,14 +1,23 @@
 #!/usr/bin/env python3
-"Script to run Haldis on a server"
+"""
+Used by Zeus in production.
+This script makes Haldis acceptable to Phusion Passenger assuming a setup like on Zeus servers.
+"""
+
+# pylint: disable=wrong-import-position
 
 import os
 import sys
 
+# User has the virtual environment in ~/env/
 INTERP = os.path.expanduser("~/env/bin/python3")
 if sys.executable != INTERP:
     os.execl(INTERP, INTERP, *sys.argv)
 
 sys.path.append(os.getcwd())
+
+# Phusion Passenger expects this file to be called `passenger_wsgi.py`
+# and the WSGI object to be called `application`
 from app import app as application
 
 # For running on the server with passenger etc