blank lines before .. versionchanged

Refs 
#22011 (comment)

Blanks are needed before but not after or in between.

Author: dhimmel

doc/source/io.rst

@@ -299,7 +299,6 @@ compression : {``'infer'``, ``'gzip'``, ``'bz2'``, ``'zip'``, ``'xz'``, ``None``
 
   .. versionadded:: 0.18.1 support for 'zip' and 'xz' compression.
   .. versionchanged:: 0.24.0 'infer' option added and set to default.
-
 thousands : str, default ``None``
   Thousands separator.
 decimal : str, default ``'.'``

pandas/core/frame.py

@@ -1755,9 +1755,9 @@ def to_csv(self, path_or_buf=None, sep=",", na_rep='', float_format=None,
             If 'infer' and `path_or_buf` is path-like, then detect compression
             from the following extensions: '.gz', '.bz2', '.zip' or '.xz'
             (otherwise no compression).
+
             .. versionchanged:: 0.24.0
                'infer' option added and set to default
-
         line_terminator : string, default ``'\n'``
             The newline character or character sequence to use in the output
             file

pandas/core/generic.py

@@ -1999,7 +1999,6 @@ def to_json(self, path_or_buf=None, orient=None, date_format=None,
             like.
 
             .. versionadded:: 0.19.0
-
         compression : {'infer', 'gzip', 'bz2', 'zip', 'xz', None},
                        default 'infer'
             A string representing the compression to use in the output file,
@@ -2008,7 +2007,6 @@ def to_json(self, path_or_buf=None, orient=None, date_format=None,
             .. versionadded:: 0.21.0
             .. versionchanged:: 0.24.0
                'infer' option added and set to default
-
         index : boolean, default True
             Whether to include the index values in the JSON string. Not
             including the index (``index=False``) is only supported when

pandas/core/series.py

@@ -3799,9 +3799,9 @@ def to_csv(self, path=None, index=True, sep=",", na_rep='',
             A string representing the compression to use in the output file.
             Allowed values are None, 'gzip', 'bz2', 'zip', 'xz', and 'infer'.
             This input is only used when the first argument is a filename.
+
             .. versionchanged:: 0.24.0
                'infer' option added and set to default
-
         date_format: string, default None
             Format string for datetime objects.
         decimal: string, default '.'