Correct Dodge the Creeps' copyright info

It originally said that "Abstract Platformer" was copyright kenny.nl.
This is not true. "Abstract Platformer" was dedicated to the public
domain using CC0. "When CC0 is applied to a work, copyright no longer
applies to the work in most jurisdictions around the world." (Source:
https://creativecommons.org/faq/#how-do-cc-licenses-operate)

It also said that "Abstract Platformer" was created in the years
2010-2020. While the "Abstract Platformer" webpage
(https://www.kenney.nl/assets/abstract-platformer) does say "Copyright ©
2010 - 2020", I believe that that's a copyright notice for the website
itself, not the asset pack. I'm not sure when Kenney started working on
"Abstract Platformer", but I'm confident that it was published in 2016
because:

 * All of the files in the ZIP archive are dated 2016.
 * "Abstract Platformer" was published to OpenGameArt.org in 2016. See:
   https://opengameart.org/content/abstract-platformer

I didn't think that it made sense to call that section of the README
"Licenses" anymore because "[...]CC0 is not a license; it is a public
domain dedication." (Source:
https://creativecommons.org/faq/#how-do-cc-licenses-operate)

2d/dodge_the_creeps/README.md

@@ -18,10 +18,10 @@ Note: There is a C# version available [here](https://github.com/godotengine/godo
 
 ![GIF from the documentation](https://docs.godotengine.org/en/latest/_images/dodge_preview.gif)
 
-## Licenses
+## Copying
 
 `art/House In a Forest Loop.ogg` Copyright © 2012 [HorrorPen](https://opengameart.org/users/horrorpen), [CC-BY 3.0: Attribution](http://creativecommons.org/licenses/by/3.0/). Source: https://opengameart.org/content/loop-house-in-a-forest
 
-Images are from "Abstract Platformer". Copyright © 2010-2020 kenney.nl, [CC0 1.0 Universal](http://creativecommons.org/publicdomain/zero/1.0/). Source: https://www.kenney.nl/assets/abstract-platformer
+Images are from "Abstract Platformer". Created in 2016 by kenney.nl, [CC0 1.0 Universal](http://creativecommons.org/publicdomain/zero/1.0/). Source: https://www.kenney.nl/assets/abstract-platformer
 
 Font is "Xolonium". Copyright &copy; 2011-2016 Severin Meyer <[email protected]>, with Reserved Font Name Xolonium, SIL open font license version 1.1. Details are in `fonts/LICENSE.txt`.