added a note for starting the ngx_openresty server.

README

@@ -71,6 +71,12 @@ in your PATH environment, and then follow the following steps:
 
         make install
 
+Then you can start your server this way:
+
+    /usr/local/openresty/nginx/sbin/nginx -p /path/to/your/server/root -c /path/to/your/nginx.conf
+
+assuming you're using the default "prefix", i.e., /usr/local/openresty, in Step 2.
+
 For bundle maintainers:
 
     The bundle's source is at the following git repository: