add info for raspberry 4 with 4GB

[bochachaner]

Since i had multiple reset with converting NEF file, i could increase the stability by changing the swap file and only use one worker.

[CLAassistant]

All committers have signed the CLA.

[lastzero]

Thanks! Could you quickly fix the typos at the end?

[bochachaner]

done

[lastzero]

Improved the wording a little :)