Missing changelog entry for the root lib from #590

Author: nedtwigg

CHANGES.md

@@ -12,6 +12,7 @@ We adhere to the [keepachangelog](https://keepachangelog.com/en/1.0.0/) format (
 ## [Unreleased]
 ### Added
 * `NodeJsGlobal.setSharedLibFolder` allows to set the location of nodejs shared libs. ([#586](https://github.com/diffplug/spotless/pull/586))
+* `PaddedCell.isClean()` returns the instance of `PaddedCell.DirtyState` which represents clean. ([#590](https://github.com/diffplug/spotless/pull/590))
 ### Fixed
 * Previously, the nodejs-based steps would throw `UnsatisfiedLinkError` if they were ever used from more than one classloader.  Now they can be used from any number of classloaders (important for gradle build daemon). ([#586](https://github.com/diffplug/spotless/pull/586))