Add documentation about the new options

Resources/doc/configuration.rst

@@ -31,6 +31,9 @@ The default configuration for the bundle looks like this:
             # Prototype
             name:
                 quality:              100
+                jpeg_quality:         ~
+                png_compression_level:  ~
+                png_compression_filter: ~
                 animated:             false
                 format:               ~
                 cache:                ~
@@ -67,7 +70,10 @@ Each filter set that you specify has the following options:
   for more information) and options that should be passed to the specific filter type.
 * ``post_processors`` - sets post-processors to be applied on filtered image
   (see Post-Processors section in the :doc:`filters chapter <filters>` for details).
-* ``quality`` - override the default quality of 100 for the generated images.
+* ``quality`` - override the default quality of 100 for the generated images. **(deprecated)**
+* ``jpeg_quality`` - override the quality for jpeg images (this overrides the ``quality`` option above)
+* ``png_compression_level`` - set the compression level for png images (0-9) (this overrides the ``quality`` option above)
+* ``png_compression_filter`` - set the compression filter for png images (see the ``filters`` parameter for ``imagepng`` function in `PHP manual`_ for more details)
 * ``cache`` - override the default cache setting.
 * ``data_loader`` - override the default data loader.
 * ``route`` - optional list of route requirements, defaults and options using in
@@ -77,3 +83,5 @@ Each filter set that you specify has the following options:
   is ignored).
 * ``animated`` - support for resizing animated gif (currently not supported by
   Imagine (PR pending))
+
+.. _`PHP Manual`: http://php.net/imagepng