s/ssalm/Psalm/

Author: Nyholm

contributing/code/pull_requests.rst

@@ -417,7 +417,7 @@ Psalm
 
 `Psalm`_ will make a comment on your Pull Request if it discovers any potential
 type errors. The Psalm errors are not always correct, but each should be reviewed
-and discussed. A Pull Request should not update the psalm baseline nor add ``@psalm-``
+and discussed. A Pull Request should not update the Psalm baseline nor add ``@psalm-``
 annotations.
 
 After the `Psalm phar is installed`_, the analysis can be run locally with: