README.md in fluent-plugin-simplearithmetic-0.0.1 vs README.md in fluent-plugin-simplearithmetic-0.0.2

@@ -3,11 +3,11 @@
 This fluentd output plugin helps you to calculate messages.
 
 This plugin is based on [fluent-plugin-datacalculator](https://github.com/muddydixon/fluent-plugin-datacalculator) written by Muddy Dixon. This plugin doesn't have a summarize function which provided by fluent-plugin-datacalculator.
 
 
-## Installaion
+## Installation
 
 ```
 $ fluent-gem install fluent-plugin-simplearithmetic
 ```
 
@@ -118,25 +118,28 @@
 
 All formulas will be evaluated as ruby sentences. Some json fields will not be fitted as ruby variables. For example, 
 
 ```
 <formulas>
-   var-1   a + b
-   var$2   c * d
+   var-1  a + b
+   var$2  c * d
+   var@   "@@@"
 </formulas>
 ```
 
 will raise an syntax error in the initialize process of fluentd.
 
-To get rid of this case, you can set `replace_hyphen` and `replace_dollar` in the configuration and formulas.
+To get rid of this case, you can set `replace_hyphen`, `replace_at` and `replace_dollar` in the configuration and formulas.
 
 ```
 replace_hyphen   __H__
 replace_dollar   __D__
+replace_at       __AT__
 
 <formulas>
-   var__H__1   a + b
-   var__D__2   c * d
+   var__H__1  a + b
+   var__D__2  c * d
+   var__AT__  "@@@"
 </formulas>
 ```
 
 
 ## Copyright