Add Spotless to Code Formatting (#1290)

* Add Spotless to formatting tools list in README

Spotless is the go to tooling for formatting and enforcement of a code style

* Update Spotless description in README.md

Author: rajneeshpatel

README.md

@@ -243,6 +243,7 @@ _Tools that format or restructure Java source code._
 - [google-java-format](https://github.com/google/google-java-format) - Reformats Java source code to follow Google Java Style.
 - [JHarmonizer](https://github.com/lemon-ant/JHarmonizer) - Safely reorders Java source code with configurable rules and Palantir Java Format.
 - [Palantir Java Format](https://github.com/palantir/palantir-java-format) - Formatter based on google-java-format with wider lines and lambda-friendly output.
+- [Spotless](https://github.com/diffplug/spotless) - A versatile code formatter for Gradle and Maven that enforces multiple styles (including Google and Palantir) across Java and other languages.
 
 ### Code Generators