docs: Remove IF block in CHECK vs. RETURN

[mauriciolauffer]

It's not clean, it may not be clear, it adds unnecessary depth. If this a clean code guide, the suggested IF block has no place here as it's worse and dirtier than the other options.

[mauriciolauffer]

PS: thanks to Jelena for starting the discussion: https://twitter.com/JelenaAtLarge/status/1527775392790204416

[larshp]

#276