change RPS

Author: duongau

includes/front-door-limits.md

@@ -87,7 +87,7 @@
 
 <sup>1</sup>If the traffic isn't globally distributed and concentrated in one or more regions, or if a higher quota limited is need, create an [Azure support request](https://portal.azure.com/#blade/Microsoft_Azure_Support/HelpAndSupportBlade/newsupportrequest).
 
-<sup>2</sup>Azure Front Door currently has a 5,000 RPS (Receive Packet Steering) per POP limit.
+<sup>2</sup>Azure Front Door currently has a 5,000 request per seconds per POP limit.
 
 #### Timeout values