docs: add japan on main page

Author: clemra

content/security/index.mdx

@@ -75,7 +75,8 @@ Langfuse is an **open‑source LLM engineering platform** that provides tracing,
 
 Langfuse Cloud mainly runs on **AWS and Clickhouse via AWS**:
 
-- **US region**: us-west-2 (Oregon)
+- **US & HIPAA region**: us-west-2 (Oregon)
 - **EU region**: eu-west-1 (Ireland)
+- **JP region**: ap-northeast-1 (Japan)
 
 Self‑hosted customers can choose any region / provider. Langfuse Self-Hosted can be run fully offline/air-gapped.