Update SSH port forward command

HPC_Python_Guide.md

@@ -171,7 +171,7 @@ You should now be able to install packages with pip install <PACKAGE> as normal.
 
 7. Open a terminal on your own computer and run
    ```
-   ssh <USERNAME>@login2.hpc.dtu.dk -g -L44000:<HOSTNAME>:44000 -N
+   ssh <USERNAME>@login2.hpc.dtu.dk -NL44000:<HOSTNAME>:44000
    ```
    where `<USERNAME>` is your DTU user name and `<HOSTNAME>` is the hostname you found in step 4.
    This should prompt you for your DTU password, _**and then NOTHING SHOULD HAPPEN**_.