Add missing unit.

Doc/whatsnew/3.3.rst

@@ -1119,7 +1119,7 @@ at http://www.bytereef.org/mpdecimal/quickstart.html.
    +---------+-------------+--------------+-------------+
    |         |  decimal.py |   _decimal   |   speedup   |
    +=========+=============+==============+=============+
-   |   pi    |    42.02    |    0.345     |    120x     |
+   |   pi    |    42.02s   |    0.345s    |    120x     |
    +---------+-------------+--------------+-------------+
    | telco   |   172.19s   |    5.68s     |     30x     |
    +---------+-------------+--------------+-------------+