Changed "uncheck" to "check" since plugin is now disabled by default

I think this was meant to be changed in 4fa9d49 but slipped by.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=221104013

Author: dverlaqueGOOG

README.md

@@ -36,7 +36,7 @@ repository.
 The plugin will be disabled by default. To enable it in the current project, go
 to `File→Settings...→google-java-format Settings` (or `IntelliJ
 IDEA→Preferences...→Other Settings→google-java-format Settings` on macOS) and
-uncheck the `Enable google-java-format` checkbox. (A notification will be
+check the `Enable google-java-format` checkbox. (A notification will be
 presented when you first open a project offering to do this for you.)
 
 To enable it by default in new projects, use `File→Other Settings→Default