Update slurm-job-submission-and-execution.md

docs.it4i/general/slurm-job-submission-and-execution.md

@@ -112,7 +112,7 @@ Example output of the job:
      36 cn20.barbora.it4i.cz
 ```
 
-## Job Environment Variables
+### Job Environment Variables
 
 Slurm provides useful information to the job via environment variables. Environment variables are available on all nodes allocated to job when accessed via Slurm supported means (srun, compatible mpirun).
 
@@ -122,7 +122,7 @@ See all Slurm variables
 $ set | grep ^SLURM
 ```
 
-### Useful Variables
+#### Useful Variables
 
 | variable name | description | example |
 | ------ | ------ | ------ |