improve wording

Author: pfistfl

contributions.md

@@ -1,7 +1,7 @@
 ### Florian Pfisterer
 
 Florian Pfisterer implemented and extended the main part of the package, heavily influcenced by
-a unpublished python code-base written in large parts by Matthew. Florian furthermore worked on the interaction with
+an unpublished python code-base written in large parts by Matthew. Florian furthermore worked on the interaction with
 **mlr3** by integrating **mlr3** learners as Auditing Mechanism as well as exporting functionality to integrate
 **mcboost** as a `PipeOp` into **mlr3pipelines**.
 
@@ -22,7 +22,7 @@ Matthew Sun wrote the initial Python implementation of MCBoost, with feedback an
 
 Michael P. Kim is a coauthor of the research papers that introduced Multi-Calibration.
 Michael oversaw the development of the initial python implementation of MCBoost
-and provided additional advice in the development of this R package.
+and provided additional advice and directions in the development of this R package.
 
 ### Bernd Bischl