upgrade go-validator to v10 for README (#2189)

Author: flysnoworg

README.md

@@ -584,7 +584,7 @@ func main() {
 
 To bind a request body into a type, use model binding. We currently support binding of JSON, XML, YAML and standard form values (foo=bar&boo=baz).
 
-Gin uses [**go-playground/validator.v8**](https://github.com/go-playground/validator) for validation. Check the full docs on tags usage [here](http://godoc.org/gopkg.in/go-playground/validator.v8#hdr-Baked_In_Validators_and_Tags).
+Gin uses [**go-playground/validator/v10**](https://github.com/go-playground/validator) for validation. Check the full docs on tags usage [here](https://godoc.org/github.com/go-playground/validator#hdr-Baked_In_Validators_and_Tags).
 
 Note that you need to set the corresponding binding tag on all fields you want to bind. For example, when binding from JSON, set `json:"fieldname"`.