chore: add usage policy

README.md

@@ -6,4 +6,6 @@ Meta library data, contains information about this instance of Gitea and stuff.
 - [FQA (Frequently Questioned Answers)](./faq.md)
 - [Credits](./credits.md)
 - Legal
-  - [Privacy Policy](https://git.soopy.moe/assets/privacy.html)
+  - [Privacy Policy](https://git.soopy.moe/assets/privacy.html)
+- Rules
+  - [Usage Policy](./usagepolicy.md)

usagepolicy.md

@@ -0,0 +1,8 @@
+# Usage policy
+This document specifies the acceptable use policy for Koumakan Library (git.soopy.moe, this service).
+
+The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", 
+"RECOMMENDED",  "MAY", and "OPTIONAL" in this document are to be interpreted as described in
+RFC 2119.
+
+*Last updated 2021-11-06 12:15:44 GMT+8*