DOC: Add description to read_csv chunksize parameter regarding number of lines in chunk (#53836)

add description to read_csv chunksize parameter

Author: tpaxman

pandas/io/parsers/readers.py

@@ -293,7 +293,8 @@
 
        ``TextFileReader`` is a context manager.
 chunksize : int, optional
-    Return ``TextFileReader`` object for iteration.
+    Number of lines to read from the file per chunk. Passing a value will cause the
+    function to return a ``TextFileReader`` object for iteration.
     See the `IO Tools docs
     <https://pandas.pydata.org/pandas-docs/stable/io.html#io-chunking>`_
     for more information on ``iterator`` and ``chunksize``.