Remove `ide` task from CONTRIBUTING
Remove `ide` task from CONTRIBUTING

In #981 the `ide` task was removed from the project. 

We considered to nudge users to start developing spotless using a particular IDE,
but users should feel free to use any development environment they like.
diffplug/spotless,diffplug/spotless,diffplug/spotless,diffplug/spotless,diffplug/spotless,diffplug/spotless