docs: fix punctuation (#37612)

MicaelJarniac · web-flow · commit 1e69e2c3cab6 · 2020-11-03T20:58:12.000-05:00
diff --git a/pandas/core/generic.py b/pandas/core/generic.py
@@ -2196,7 +2196,7 @@ def to_json(
             * Series:
 
                 - default is 'index'
-                - allowed values are: {'split','records','index','table'}.
+                - allowed values are: {'split', 'records', 'index', 'table'}.
 
             * DataFrame:
 
