Update README.md on Comment data

Author: sappho192

README.md

@@ -14,15 +14,20 @@ Usage: WXRGenerator [options...]
 Options:
 
 * -i, --input `<String>`: [Required] Filepath of the input CSV data
+* -c, --comment `<String>`: [Required] Directory path of comments CSV data
 * -m, --metadata `<String>`: [Required] Filepath of CSV metadata
 * -o, --output `<String>`: [Required] Filepath of the output XML file
 
 Example:
 
-`dotnet WXRGenerator.dll  -i "D:\temp\wp\input.csv" -m "D:temp\wp\metadata.csv" -o "D:\temp\wp\output.xml"`
+`dotnet WXRGenerator.dll  -i "D:\temp\wp\input.csv" -c "D:\temp\wp\comments" -m "D:temp\wp\metadata.csv" -o "D:\temp\wp\output.xml"`
 
 After the program have successfully finished, you can upload the file in Import page in WordPress blog and it will work
 
 # Required data
 
-Please check `example/input.csv` and `example/metadata.csv` and prepare data files like them.
+Please check `example/input.csv`, `example/metadata.csv`, and `example/comments` to prepare data files like them.
+
+Filename of comment corresponds to `uniqueId` of input post data.
+
+For example, if `uniqueId` of a post data is `2`, then corresponding comment CSV data should be prepared in `comments/2.csv`.