Clarify license

docs/README.md

@@ -11,18 +11,22 @@ This is a repository created by Sawaratsuki to upload logos of various services.
 > [!NOTE]
 > ### Summary:
 > - You are free to use this logo for non-commercial, non-profit purposes.
-    >   For example, you can use it for printing as stickers, as icons for editors, etc.
+>   For example, you can use it for printing as stickers, as icons for editors, etc.
+> - Please give the appropriate credits!
+>   You are free to modify or remix it, but you must license that new work under the same license as this original logo.
 > - If you create something using this logo, mentioning [Sawaratsuki](https://x.com/sawaratsuki1004) when posting would be motivating!
 
 ### All items
+![CC BY-NC-SA 4.0](https://mirrors.creativecommons.org/presskit/buttons/88x31/png/by-nc-sa.png)
 1. The creator of these logos is Sawaratsuki. The copyright has not been completely waived.
-2. Anyone is free to use these logos within the scope of non-profit purposes.
+2. These logos are provided under [Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)](https://creativecommons.org/licenses/by-nc-sa/4.0/deed.en).
+>  It is recommended to give appropriate credit. It is a great motivator, so please do so.
+>  You can modify or remix it, but you must give the new work the same license (CC BY-NC-SA 4.0) as the original work.
 >  Commercial use (such as selling products using the logo) is prohibited. However, it can be sold if it falls under the following conditions:
 >  1. If the official of each service wants to sell for profit
 >  2. If permission is granted by Sawaratsuki  
       > (If you find any violations, please contact [@Sawaratsuki](https://x.com/sawaratsuki1004) immediately!)
 3. It's okay to use stickers, seals, etc., for personal use without permission!
-4. Although it is optional, please credit the source. (It will be motivating.)
 
 # Want a logo that's not here!
 Please post it in the issues. We'll create it once confirmed.