fixing hardcoded home dir

[krachwal]

Changing the home dir to the GitHub Secret value instead of having it hardcoded in scp/ssh commands (this is what was failing when we met).

While I was in there, I also:

• updated step descriptions
• added Docker install ( I had done this manually on my own server so I neglected to include it in this workflow 😅 )
• added Docker prune command to save disk space (Docker leaves images and containers behind until you clean them up)