Update job-scheduling.md

docs.it4i/cs/job-scheduling.md

@@ -46,7 +46,8 @@ See all Slurm variables
 set | grep ^SLURM
 ```
 
-Useful Slurm variables
+### Useful Slurm variables
+
 | variable name | description | example |
 | ------ | ------ | ------ |
 |SLURM_JOBID| job id of the executing job| 593 |