Merged documentation update from 3.6.

Doc/library/logging.handlers.rst

@@ -282,16 +282,17 @@ module, supports rotation of disk log files.
    You can use the *maxBytes* and *backupCount* values to allow the file to
    :dfn:`rollover` at a predetermined size. When the size is about to be exceeded,
    the file is closed and a new file is silently opened for output. Rollover occurs
-   whenever the current log file is nearly *maxBytes* in length; if either of
-   *maxBytes* or *backupCount* is zero, rollover never occurs.  If *backupCount*
-   is non-zero, the system will save old log files by appending the extensions
-   '.1', '.2' etc., to the filename. For example, with a *backupCount* of 5 and
-   a base file name of :file:`app.log`, you would get :file:`app.log`,
+   whenever the current log file is nearly *maxBytes* in length; but if either of
+   *maxBytes* or *backupCount* is zero, rollover never occurs, so you generally want
+   to set *backupCount* to at least 1, and have a non-zero *maxBytes*.
+   When *backupCount* is non-zero, the system will save old log files by appending
+   the extensions '.1', '.2' etc., to the filename. For example, with a *backupCount*
+   of 5 and a base file name of :file:`app.log`, you would get :file:`app.log`,
    :file:`app.log.1`, :file:`app.log.2`, up to :file:`app.log.5`. The file being
    written to is always :file:`app.log`.  When this file is filled, it is closed
    and renamed to :file:`app.log.1`, and if files :file:`app.log.1`,
-   :file:`app.log.2`, etc.  exist, then they are renamed to :file:`app.log.2`,
-   :file:`app.log.3` etc.  respectively.
+   :file:`app.log.2`, etc. exist, then they are renamed to :file:`app.log.2`,
+   :file:`app.log.3` etc. respectively.
 
    .. versionchanged:: 3.6
       As well as string values, :class:`~pathlib.Path` objects are also accepted