doc: fixed a typo in the code sample.

Signed-off-by: Yichun Zhang (agentzh) <agentzh@gmail.com>

Author: luanote

README.markdown

@@ -41,7 +41,7 @@ Synopsis
 ========
 
 ```lua
- lua_package_path "/path/to/lua-resty-redis/lib/?.lua;;";
+ lua_package_path "/path/to/lua-resty-upload/lib/?.lua;;";
 
  server {
  location /test {