Fix markdownlint

Signed-off-by: Florian Hotze <[email protected]>

CONTRIBUTING.md

@@ -56,7 +56,7 @@ Pull requests descriptions should be as clear as possible and include a referenc
 
 Pull requests must not contain commits from other users or branches.
 
-Commit messages must start with a capitalized and short summary (max. 50 chars) written in the imperative, 
+Commit messages must start with a capitalized and short summary (max. 50 chars) written in the imperative,
 followed by an optional, more detailed explanatory text which is separated from the summary by an empty line.
 
 Code review comments may be added to your pull request.