Update FAQ with bitmap resolution question

Please put question and answer to the FAQ section regarding the use of the bitmaps (inspired by the recent inhouse feedback)

Something like this, feel free to reword everything

case: user has default size for a safe image 100x100, and in some state the image is scaled to 200x200. 

Q: How I can ensure that the safe image looks smooth when scaling it up?

A: Please use the source image that has the resolution for the maximum planned size. This way you can avoid up-scaling effects on the image sharpness.

Reasoning: The tooling can do downscaling for the image, so source image with 200x200 size looks good when using it in 200x200 or in 100x100 size. But source image with 100x100 size does not look so good when using it in 200x200 size.