update README.md for JDK 16+ issues (#1573)

README.md

@@ -74,11 +74,11 @@ $ ./ktlint -R diktat.jar --disabled_rules=standard "dir/your/dir/**/*.kt"
 To **autofix** all code style violations, use `-F` option.
 
 ## Run with Maven using diktat-maven-plugin
-:heavy_exclamation_mark: If you are using **Java 16+**, you need to add `--add-opens java.base/java.util=ALL-UNNAMED` flag to the JVM. For more information, see: https://github.com/pinterest/ktlint/issues/1195
+:heavy_exclamation_mark: If you are using **Java 16+**, you need to add `--add-opens java.base/java.util=ALL-UNNAMED --add-opens=java.base/java.lang=ALL-UNNAMED` flag to the JVM. For more information, see: https://github.com/pinterest/ktlint/issues/1195
 This can be done by setting `MAVEN_OPTS` variable:
 
 ```
-export MAVEN_OPTS="--add-opens java.base/java.util=ALL-UNNAMED"
+export MAVEN_OPTS="--add-opens java.base/java.util=ALL-UNNAMED --add-opens=java.base/java.lang=ALL-UNNAMED"
 ```
 
 This plugin is available since version 0.1.3. You can see how it is configured in our project for self-checks: [pom.xml](pom.xml).