Added some usage information.

README.md

@@ -4,6 +4,23 @@ Tool for giving a quick overview of Slurm job statistics.
 Inspired by https://github.com/birc-aeh/slurm-utils/blob/master/jobinfo
 from Anders Halager  <aeh@birc.au.dk>
 
+# Usage
+
+```
+jobinfo [-h] [-d] [-l] jobid`
+
+collates job information from the 'sstat', 'sacct' and 'squeue' SLURM commands
+to give a uniform interface for both current and historical jobs.
+
+positional arguments:
+  jobid        the jobid to query
+
+optional arguments:
+  -h, --help   show this help message and exit
+  -d, --debug  Shows extra information about how the data is gathered
+  -l, --long   Shows more information about the job
+```
+
 # Release notes:
 
 ## v1.0 - 2024-04-15