docs: add a note about JSON Schema

Author: ldez

docs/src/docs/configuration/configuration.mdx

@@ -31,6 +31,8 @@ You can configure specific linters' options only within the config file (not the
 There is a [`.golangci.reference.yml`](https://github.com/golangci/golangci-lint/blob/master/.golangci.reference.yml) file with all supported options, their description, and default values.
 This file is neither a working example nor a recommended configuration, it's just a reference to display all the configuration options.
 
+The configuration file can be validated with the JSON Schema: https://golangci-lint.run/jsonschema/golangci.jsonschema.json
+
 { .ConfigurationExample }
 
 ## Command-Line Options