DOC: add default encoding to read_csv (#50661)

Author: marielledado

pandas/io/parsers/readers.py

@@ -317,7 +317,7 @@
     `skiprows`. For example, if ``comment='#'``, parsing
     ``#empty\\na,b,c\\n1,2,3`` with ``header=0`` will result in 'a,b,c' being
     treated as the header.
-encoding : str, optional
+encoding : str, optional, default "utf-8"
     Encoding to use for UTF when reading/writing (ex. 'utf-8'). `List of Python
     standard encodings
     <https://docs.python.org/3/library/codecs.html#standard-encodings>`_ .