README mentions iterating on eclipse.xml (#848)

README.md

@@ -318,6 +318,8 @@ spotless {
 
 We chose the Eclipse formatter because it can be run from the command line and from both IDEs (IntelliJ using the [Eclipse Code Formatter](https://plugins.jetbrains.com/plugin/6546-eclipse-code-formatter) plugin).
 
+To iterate on the eclipse.xml formatter config, you can import it into an instance of Eclipse, edit it through the preferences UI and then export it, or you can manually tune individual values by referring to the master list of [DefaultCodeFormatterConstants](https://github.com/eclipse/eclipse.jdt.core/blob/6a8cee1126829229d648db4ae0e5a6b70a5d4f13/org.eclipse.jdt.core/formatter/org/eclipse/jdt/core/formatter/DefaultCodeFormatterConstants.java) and [DefaultCodeFormatterOptions](https://github.com/eclipse/eclipse.jdt.core/blob/6a8cee1126829229d648db4ae0e5a6b70a5d4f13/org.eclipse.jdt.core/formatter/org/eclipse/jdt/internal/formatter/DefaultCodeFormatterOptions.java#L41-L95). Running `./gradlew :gradle-baseline-java:test -Drecreate=true` should update all the checked-in snapshot test cases.
+
 ## com.palantir.baseline-reproducibility
 
 This plugin is a shorthand for the following snippet, which opts-in to reproducible behaviour for all Gradle's Jar, Tar and Zip tasks. (Surprisingly, these tasks are not reproducible by default).