Add instruction to add disableStaticImages: true

[devanshj]

This documents the fix to #251 (I'm not sure if that's enough to close the issue). Someone who knows more about the issue should word this more concretely with more information if required. So consider this as "draft".

I just wanted to get this in readme because I myself spent way too long trying to fix it, apparently initially it didn't even show any errors it's only when I tried it on a fresh create-next-app project it showed this error and then I landed on the issue page.

Thanks a lot for this plugin, I like it a lot especially more than next/image because this is more primitive and I'm in control of things!

[ernie-blockswap]

Just stumbled upon this problem.

Could you please merge the fix?:)