Update slurm on barbora date/time

docs.it4i/general/resource_allocation_and_job_execution.md

 # Resource Allocation and Job Execution
 
 !!! important "Barbora migrating to Slurm"
-    Starting July 17., we are migrating the Barbora's workload manager **from PBS to Slurm**.
+    Starting July 19. 9AM, we are migrating the Barbora's workload manager **from PBS to Slurm**.
     For more information on how to submit jobs in Slurm, see the [Slurm Job Submission and Execution][8] section.
 
 To run a [job][1], computational resources for this particular job must be allocated. This is done via the [PBS Pro][b] job workload manager software, which distributes workloads across the supercomputer. Extensive information about PBS Pro can be found in the [PBS Pro User's Guide][2].