Fix VPS -> nginx deployment tips (#581)

`alias` field should be end with '/' in nginx.conf.
Or nginx server doesn't work.

Author: IceHe

docs/deploy.md

@@ -68,7 +68,7 @@ server {
   server_name  your.domain.com;
 
   location / {
-    alias /path/to/dir/of/docs;
+    alias /path/to/dir/of/docs/;
     index index.html;
   }
 }