Change order of allow rule in robots.txt

I think this is the proper order. Don't know if it matters, but it is not bad to change it in any case.

robots.txt

@@ -1,4 +1,4 @@
 # Might as well keep robots away for performance and privacy reasons.
 User-agent: *
-Allow: /index.php
 Disallow: /
+Allow: /index.php