README.md in fluent-plugin-groupcounter-0.2.0 vs README.md in fluent-plugin-groupcounter-0.2.1

@@ -5,11 +5,11 @@
 ## Configuration
 
 Assume inputs are coming as followings:
 
     apache.access: {"code":"200", "method":"GET", "path":"/index.html", "reqtime":"1.001" }
-    apache.access: {"code":"404", "method":"GET", "path":"/foo.html",   "reqtime":"2.002" }
+    apache.access: {"code":"202", "method":"GET", "path":"/foo.html",   "reqtime":"2.002" }
     apache.access: {"code":"200", "method":"GET", "path":"/index.html", "reqtime":"3.003" }
 
 Think of quering `SELECT COUNT(\*) GROUP BY code,method,path`. Configuration becomes as below:
 
     <match apache.access>
@@ -20,11 +20,11 @@
       group_by_keys code,method,path
     </match>
 
 Output becomes like
 
-    groupcounter.apache.access: {"200_GET_/index.html_count":2, "404_GET_/foo.html_count":1}
+    groupcounter.apache.access: {"200_GET_/index.html_count":2, "202_GET_/foo.html_count":1}
 
 ## Parameters
 
 * group\_by\_keys (semi-required)
 
@@ -32,10 +32,20 @@
 
 * delimiter
 
     Specify the delimiter to join `group_by_keys`. Default is '_'.
 
+* pattern\[1-20\]
+
+    Use `patternX` option to apply grouping more roughly. For example, adding a configuration for the above example as below
+
+         pattern1 2xx ^2\d\d
+
+    gives you an ouput like
+
+         groupcounter.apache.access: {"2xx_GET_/index.html_count":3}
+
 * group\_by\_expression (semi-required)
 
     Use an expression to group the event record. `group_by_keys` or `group_by_expression` is required.
 
     For examples, for the exampled input above, the configuration as below
@@ -87,10 +97,10 @@
 
         max_key reqtime
 
     gives you an output like
 
-        groupcounter.apache.access: {"200_GET_/index.html_reqtime_max":3.003, "404_GET_/foo.html_reqtime_max":2.002}
+        groupcounter.apache.access: {"200_GET_/index.html_reqtime_max":3.003, "202_GET_/foo.html_reqtime_max":2.002}
 
 * min\_key
 
     Specify key name in the event record to do `SELECT COUNT(\*),MIN(key_name) GROUP BY`.