Updates the README to allow NC clause contributions (#4653)

I was going through our assets and noticed that we've accepted some NC
assets over time, and we don't really have an issue with allowing NC
assets since we're not monitizing them.

- Specifies we also accept CY-BY-NC 3.0 Licenses. We've ported sprites
that have a non-commerical clauses (kitty borgs)

The only license we'd have an issue supporting is the No Derivatives
clause.

This isn't a game facing change.

README.md

@@ -21,6 +21,8 @@ This is Bubberstation's fork of TG. Originally forked from Skyrat.
 
 Space Station 13 is a paranoia-laden round-based roleplaying game set against the backdrop of a nonsensical, metal death trap masquerading as a space station, with charming spritework designed to represent the sci-fi setting and its dangerous undertones. Have fun, and survive!
 
+As of our recent split from Skyrat, a lot of codedocs/modularization guides need to be rewritten. Until it is done expect some wait time with larger refactors. You are also free to edit any Skyrat files
+
 ## Contribution Rules and Guidelines
 
 **1. Do Not Be A Dick**
@@ -35,7 +37,7 @@ Space Station 13 is a paranoia-laden round-based roleplaying game set against th
 - All asset files (images and sound) are **CC-BY-SA 3.0** unless otherwise stated
 - The license information, including the MIT license and its exceptions, can be found at the bottom of this readme.
 - What does this mean to our contributors? **The** [GNU AGPL V3](https://www.gnu.org/licenses/agpl-3.0.html) **licensing on this codebase is non-negotiable** and **irrevocable** the moment you open a PR. We are incapable of privatizing this codebase and you are incapable of restricting your code contributions even if you close the PR. Do not open a contribution if you do not feel comfortable with your code being permanent across the entirety of the community. **All contributions are preserved in commit history**
-- What does this mean to our spriters and sound designers? [CC-BY-SA 3.0](https://creativecommons.org/licenses/by-sa/3.0/) **is the only license that this project will accept**
+- What does this mean to our spriters and sound designers? [CC-BY-SA 3.0](https://creativecommons.org/licenses/by-sa/3.0/) or [CY-BY-NC-SA 3.0](https://creativecommons.org/licenses/by-nc/3.0/deed.en) (must be declared appropriately) **are the only licenses that this project will accept.**
 - It is prohibited to use the attribution requirement to [suggest that you endorse or support a particular use](https://creativecommons.org/faq/#do-i-need-to-be-aware-of-anything-else-when-providing-attribution) of your assets.
 - You are entitled to credit yourself with comments and you are entitled to waive the attribution requirement choosing not to be identified as the creator if you wish.
 - If you do not like how your assets were modified or used, it is required that the other person [remove the attribution information upon request](https://wiki.creativecommons.org/wiki/License_Versions#Licensors_may_request_removal_of_attribution).
@@ -44,10 +46,9 @@ Space Station 13 is a paranoia-laden round-based roleplaying game set against th
 
 _Credit: [Goonstation contribution guidelines](https://hackmd.io/@goonstation/docs/%2F%40goonstation%2Fcontribute#What-if-I-change-my-mind-about-my-contributions-being-published)_
 
+To forward any licensing concerns, please open an issue report or pull request. Alternatively, you can join our [Discord](https://discord.gg/AvjrTqnqEx) and contact the project leaders.
 ## Modularization and codedocs note
 
-As of our recent split from Skyrat, a lot of codedocs/modularization guides need to be rewritten. Until it is done expect some wait time with larger refactors. You are also free to edit any Skyrat files
-
 ## Important note - TEST YOUR PULL REQUESTS
 
 You are responsible for the testing of your content. You should not mark a pull request ready for review until you have actually tested it. If you require a separate client for testing, you can use a guest account by logging out of BYOND and connecting to your test server.