aceh 增加 purpose 字段

api.conf

@@ -22,7 +22,7 @@ location = /preflight {
   more_set_headers
     'access-control-allow-origin: *'
     'access-control-allow-methods: GET,POST,PUT,PATCH,TRACE,DELETE,HEAD,OPTIONS'
-    'access-control-allow-headers: --raw-info,--level,--url,--referer,--cookie,--origin,--ext,--aceh,--ver,--type,--mode,accept,accept-charset,accept-encoding,accept-language,accept-datetime,authorization,cache-control,content-length,content-type,date,if-match,if-modified-since,if-none-match,if-range,if-unmodified-since,max-forwards,pragma,range,te,upgrade,upgrade-insecure-requests,x-requested-with,chrome-proxy'
+    'access-control-allow-headers: --raw-info,--level,--url,--referer,--cookie,--origin,--ext,--aceh,--ver,--type,--mode,accept,accept-charset,accept-encoding,accept-language,accept-datetime,authorization,cache-control,content-length,content-type,date,if-match,if-modified-since,if-none-match,if-range,if-unmodified-since,max-forwards,pragma,range,te,upgrade,upgrade-insecure-requests,x-requested-with,chrome-proxy,purpose'
     'access-control-max-age: 1728000'
   ;
   return              204;