Update README.md

Author: Moh Khoirul Anam

README.md

@@ -41,7 +41,7 @@ boolean `$setIndexSheetByName` to set the sheet index by sheet name or array res
 
 string `$getOnlySheet` is a sheet name to getting the data. This is only get the sheet with same name.
 
-array|Formatter $formatter the formatter used to format model attribute values into displayable texts. This can be either an instance of [[Formatter]] or an configuration array for creating the [[Formatter]] instance. If this property is not set, the "formatter" application component will be used.
+array|Formatter `$formatter` the formatter used to format model attribute values into displayable texts. This can be either an instance of [[Formatter]] or an configuration array for creating the [[Formatter]] instance. If this property is not set, the "formatter" application component will be used.
 
 Installation
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@@ -238,4 +238,4 @@ Array([file1] => Array([Sheet1] => Array([0] => Array([name] => Anam, [email] =>
 
 TODO
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-- Adding footer params for columns in exporting data.
+- Adding footer params for columns in exporting data.