fid -> id

Author: libaoxi

lib/config.js

@@ -77,8 +77,8 @@ const DEFAULT_CONFIG = {
     lang:   'cpp'
   },
   file: {
-    show:       '${fid}.${slug}',
-    submission: '${fid}.${slug}.${sid}.${ac}'
+    show:       '${id}.${slug}',
+    submission: '${id}.${slug}.${sid}.${ac}'
   },
   color: {
     enable: true,