Replace UNIX_HPC_cheat_sheet.md

exercises/UNIX_HPC_cheat_sheet.md

@@ -54,8 +54,6 @@ echo "foo" > bar.txt        # Direct output into file. Overwrites file if it alr
 echo "foo" >> bar.txt       # Direct output into file and append if it already exists. 
 command1 | command2         # Directs output from command1 as standard input into command2    
 ```
-<br><br>
-
 
 ## Variables and arrays
 
@@ -105,7 +103,7 @@ my_software_container.sif my_software [parameters]
 ```
 
 
-<br>
+<br><br>
 
 # SLURM Cheat Sheet