re-enable hash on last rc script

[Madalosso]

The configuration on ~/.local/share/omakub/defaults/bash/shell, sourced by defaults/bash/rc disables hash.
The change introduced here re-enables it as part of the last script executed by rc.

Fixes #339

As disclosed at the issue:

I'm unfamiliar with the usage of hash within these configuration files, nor do I have a clear idea where a hash -h should be placed to re-enable the command without undoing the intended goal with the disabled. Still, I assume it's a simple fix for whoever has context on its usage.

So please review it carefully as I might be ignoring important aspects of how this suppose to be used