feature symfony#4206 Added note about ProgressBar changes (kbond)

This PR was merged into the master branch.

Discussion
----------

Added note about ProgressBar changes

| Q             | A
| ------------- | ---
| Doc fix?      | no
| New docs?     | symfony/symfony#11852
| Applies to    | 2.6
| Fixed tickets | n/a

Commits
-------

4e2142d Added note about ProgressBar changes

Author: weaverryan

components/console/helpers/progressbar.rst

@@ -46,8 +46,16 @@ you can also set the current progress by calling the
 
 .. caution::
 
-    The progress bar only works if your platform supports ANSI codes; on other
-    platforms, no output is generated.
+    Prior to version 2.6, the progress bar only works if your platform
+    supports ANSI codes; on other platforms, no output is generated.
+
+.. versionadded:: 2.6
+    If your platform doesn't support ANSI codes, updates to the progress
+    bar are added as new lines. To prevent the output from being flooded,
+    adjust the
+    :method:`Symfony\\Component\\Console\\Helper\\ProgressBar::setRedrawFrequency`
+    accordingly. By default, when using a ``max``, the redraw frequency
+    is set to *10%* of your ``max``.
 
 If you don't know the number of steps in advance, just omit the steps argument
 when creating the :class:`Symfony\\Component\\Console\\Helper\\ProgressBar`