Include new source plugins and settings in the documentation

Author: ohinckel

docs/en/config.md

@@ -52,6 +52,12 @@ Should point to a directory where the application can store some data. Please
 do not point this to a temporary directory. It will contain persistent data
 which should not be deleted.
 
+#### `FRAMARAMA.MEDIA_PATH`
+
+Default: `./data/media/`
+
+Points to a directory where some media files can be placed to read. The directory
+source plugin will read the files located in this directory.
 
 
 ### Server

docs/en/server/plugins/source.md

@@ -22,6 +22,14 @@ Common fields for all source steps:
 * mime_out - if required provide mime type of output data
 * loop_out - flag if following steps should loop over generated output data
 
+## dir
+
+Read list of files from a given directory.
+
+Fields:
+* path - the path to read (relative to media directory)
+* filter_files - the pattern to filter files (defaults to JPEG pattern)
+
 ## data
 
 Manipulates a given input data (e.g. a CSV list) and convert/filter/strip data