Update zlib.rst

Author: Dreamsorcerer

Doc/library/zlib.rst

@@ -308,6 +308,11 @@ Decompression objects support the following methods and attributes:
    :attr:`unconsumed_tail`. This bytestring must be passed to a subsequent call to
    :meth:`decompress` if decompression is to continue.  If *max_length* is zero
    then the whole input is decompressed, and :attr:`unconsumed_tail` is empty.
+   For example, the complete body could be read like::
+
+     process_output(d.decompress(data, max_length))
+     while d.unconsumed_tail:
+         process_output(d.decompress(d.unconsumed_tail, max_length))
 
    .. versionchanged:: 3.6
       *max_length* can be used as a keyword argument.