dataframe parameter in px docstrings (#1932)

Author: emmanuelle

Diff for: packages/python/plotly/plotly/express/_doc.py

@@ -22,6 +22,7 @@
         "DataFrame or array-like or dict",
         "This argument needs to be passed for column names (and not keyword names) to be used.",
         "Array-like and dict are tranformed internally to a pandas DataFrame.",
+        "Optional: if missing, a DataFrame gets constructed under the hood using the other arguments.",
     ],
     x=[
         colref_type,