README.md in fluent-plugin-groupcounter-0.2.2 vs README.md in fluent-plugin-groupcounter-0.2.3

@@ -14,11 +14,11 @@
 
     <match apache.access>
       type groupcounter
       aggregate tag
       output_per_tag true
-      tag_prefix groupcounter
+      add_tag_prefix groupcounter
       group_by_keys code,method,path
     </match>
 
 Output becomes like
 
@@ -66,15 +66,15 @@
 
 * tag
 
     The output tag. Default is `groupcount`.
 
-* tag\_prefix
+* add\_tag\_prefix
 
     The prefix string which will be added to the input tag. `output_per_tag yes` must be specified together. 
 
-* input\_tag\_remove\_prefix
+* remove\_tag\__prefix
 
     The prefix string which will be removed from the input tag.
 
 * count\_interval
 
@@ -122,9 +122,21 @@
     Default is `_min`. Should be used with `min_key` option.
 
 * avg\_suffix
 
     Default is `_avg`. Should be used with `avg_key` option.
+
+## ChangeLog
+
+See [CHANGELOG.md](CHANGELOG.md) for details.
+
+## Contributing
+
+1. Fork it
+2. Create your feature branch (`git checkout -b my-new-feature`)
+3. Commit your changes (`git commit -am 'Add some feature'`)
+4. Push to the branch (`git push origin my-new-feature`)
+5. Create new [Pull Request](../../pull/new/master)
 
 ## Copyright
 
 * Copyright
   * Copyright (c) 2012- Ryosuke IWANAGA (riywo)