update README

Author: codeDebugTest

README.md

@@ -6,4 +6,7 @@ a git diff component
 ### diff result
 ![add delete file](https://github.com/codeDebugTest/vue-diff-view/raw/master/screenshots/add_delete.png)
 
-![modify file](https://github.com/codeDebugTest/vue-diff-view/raw/master/screenshots/modify.png)
+![modify file](https://github.com/codeDebugTest/vue-diff-view/raw/master/screenshots/modify.png)
+
+### todo
+when select code, not trigger line number.