Add documentation to run_simulation.py, fix typos and bug in run_example.py

run_example.py

-From multiarea_model import MultiAreaModel
+from multiarea_model import MultiAreaModel
 from start_jobs import start_job
 from config import submit_cmd, jobscript_template
 

run_simulation.py

+"""
+This script is used to run a simulation from the given command-line
+arguments:
+1. Label of the simulation
+2. Label of the network to be simulated
+
+It initializes the network class and then runs the simulate method of
+the simulation class instance.
+
+This script should be used in the `jobscript_template` defined in the
+config.py file. See config_template.py.
+"""
+
 import json
 import nest
 import os

start_jobs.py

@@ -24,7 +24,7 @@ def start_job(label, submit_cmd, jobscript_template, sumatra=False, reason=None,
         identified by the label.
     submit_cmd : str
         Submit command of the queueing system used.
-    job_script_template : formatted str
+    jobscript_template : formatted str
         Formatted string defining the template for the job script.
         Can include the following keyword arguments:
             sim_dir : str