feat(setting): add 'Document Link' option i18n support

web/src/i18n/locales/en.json

@@ -193,6 +193,8 @@
   "通用设置": "General Settings",
   "充值链接": "Recharge Link",
   "例如发卡网站的购买链接": "E.g., purchase link from card issuing website",
+  "文档地址": "Document Link",
+  "例如 https://docs.newapi.pro": "E.g., https://docs.newapi.pro",
   "聊天页面链接": "Chat Page Link",
   "例如 ChatGPT Next Web 的部署地址": "E.g., ChatGPT Next Web deployment address",
   "单位美元额度": "Quota per USD",