fix typo: "Python'd" -> "Python's"
diff --git a/docs/contributing.rst b/docs/contributing.rst
index 7ddbdcf24e8..1398e818c75 100644
--- a/docs/contributing.rst
+++ b/docs/contributing.rst
@@ -61,7 +61,7 @@ The following tools are there to help you:
 
 - For debugging, we recommend ``pip install ipdb`` and putting
   ``import ipdb; ipdb.set_trace()`` statement inside the source
-  code. Alternatively, you can use Python'd standard library `pdb`,
+  code. Alternatively, you can use Python's standard library `pdb`,
   but you won't get TAB completion...
 
 
