minor #14868 [Serializer] Update serializer.rst (souhail-5)

This PR was submitted for the 5.2 branch but it was merged into the 4.4 branch instead.

Discussion
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[Serializer] Update serializer.rst

Update CsvEncoder's default values.

Not really sure for the `empty string` mention.
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Commits
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425495b Update serializer.rst

Author: javiereguiluz

components/serializer.rst

@@ -869,7 +869,7 @@ Option                  Description                                            D
 ``csv_delimiter``       Sets the field delimiter separating values (one        ``,``
                         character only)
 ``csv_enclosure``       Sets the field enclosure (one character only)          ``"``
-``csv_escape_char``     Sets the escape character (at most one character)
+``csv_escape_char``     Sets the escape character (at most one character)      empty string
 ``csv_key_separator``   Sets the separator for array's keys during its         ``.``
                         flattening
 ``csv_headers``         Sets the order of the header and data columns
@@ -879,7 +879,7 @@ Option                  Description                                            D
                         ``a,b,c\n1,2,3``                                       ``[]``, inferred from input data's keys
 ``csv_escape_formulas`` Escapes fields containg formulas by prepending them    ``false``
                         with a ``\t`` character
-``as_collection``       Always returns results as a collection, even if only
+``as_collection``       Always returns results as a collection, even if only   ``true``
                         one line is decoded.
 ``no_headers``          Disables header in the encoded CSV                     ``false``
 ``output_utf8_bom``     Outputs special `UTF-8 BOM`_ along with encoded data   ``false``