Added hit effect.

This game is black and white, so I added hit effects to make it a little gorgeous 🌟

Since fighting games sell flashy performances, I think it's more popular to put out many effects with a focus on appearance, but DARK BOUT is a relatively slow game, so I made it a less flashy effect.

However, it may be flashy depending on future developments 😅

Also, since the game engine I'm using doesn't tell me the coordinates at which it hits, I'm just putting out an effect at the position of the hit judgment, but it worked quite well.

This hit effect will be added in the next version upgrade.