doc: Fix typo in README.md (#1926)

README.md

@@ -113,7 +113,7 @@ After running the demo for a while, you can see the following records in `~/logs
 1529998908000|2018-06-26 15:41:48|HelloWorld|20|19502|20|0|0   |0
 1529998909000|2018-06-26 15:41:49|HelloWorld|20|18386|20|0|0   |0
 
-p stands for incoming request, block for blocked by rules, success for success handled by Sentinel, e for exception count, rt for average response time (ms), occupied stands for occupiedPassQps since 1.5.0 which enable us booking more than 1 shot when entering.
+p stands for incoming request, block for blocked by rules, s for success handled by Sentinel, e for exception count, rt for average response time (ms), occupied stands for occupiedPassQps since 1.5.0 which enable us booking more than 1 shot when entering.
 ```
 
 This shows that the demo can print "hello world" 20 times per second.