Update README.md

Author: sebffischer

README.md

@@ -99,7 +99,7 @@ If your learner is not listed here but capable of extracting variable
 importance from the fitted model, the reason is most likely that it is
 not yet integrated in the package
 [mlr3learners](https://github.com/mlr-org/mlr3learners) or the [extra
-learner organization](https://github.com/mlr-org/mlr3extralearners).
+learner extension](https://github.com/mlr-org/mlr3extralearners).
 Please open an issue so we can add your package.
 
 Some learners need to have their variable importance measure “activated”