Add "Defold for Unity users"

[aglitchman]

Given recent events, Unity developers will want to try alternative engines. I suggest writing a short introduction to Defold for Unity developers to help them get started faster.

Similar to the https://defold.com/manuals/flash/ page or to
Gamefromscratch's https://www.youtube.com/watch?v=_L711ozxQbw video.

[aglitchman]

GameMaker's tutorial https://gamemaker.io/en/tutorials/moving-from-unity-to-gamemaker

[britzl]

Yes, I'd really like to see this. We need help from someone who is fluent in both Defold and Unity though...

[paweljarosz]

I'm on it rn