Why is the switch drawn like this (NRST, STM32)?
Many pcb mount push buttons are 4 pin, mostly for mechanical stability (as far as I'm aware). They are often internally connected like this (i.e. the pins on each of the two sides are connected together). Since you have the pins anyway, you might as well connect them together externally as well just in case you want to use a different switch where they aren't connected together internally.