Clarify monthly credits vs top up credits.

Author: robinjhuang

interface/credits.mdx

@@ -90,6 +90,8 @@ After completing the payment, please return to `Menu` -> `Credits` to check if y
   </Accordion>
 
   <Accordion title="Do credits expire?">
-  Yes, credits expire 1 year from the date of purchase
+  Yes, the expiration depends on the type of credits:
+  - **Monthly credits**: Expire at the end of your billing period
+  - **Top-up credits**: Expire 1 year from the date of purchase
   </Accordion>
 </AccordionGroup>

zh-CN/interface/credits.mdx

@@ -90,6 +90,8 @@ ComfyUI将始终保持完全开源，并对本地用户免费。
   </Accordion>
 
   <Accordion title="积分会过期吗？">
-  会的，积分在购买之日起1年后过期
+  会的，过期时间取决于积分类型：
+  - **月度积分**：在账单周期结束时过期
+  - **充值积分**：在购买之日起1年后过期
   </Accordion>
 </AccordionGroup>