Add a guide to the Wiki on the preferred method for floppy preservation

[Burrito78]

I'm using different Greaseweazles for years now and i dumped SCP images and converted them in HxC to IMG because I thought this was the best method.

But recently I learned that I should instead use:

gw read --format ibm.1440 --raw NAME_00.0.raw (for example)

As this creates a kfx dump (preferred by the preservation community) and verifies the raw data against format for instant error detection.

And then convert using:

gw convert --format=ibm.1440 NAME_00.0.raw NAME.img

As this has better clock recovery than HxC and therefore can work better in critical cases.

Would it be possible to do a short writeup for people just looking for the best settings for a few popular formats?

Thanks,
Burrito78