adds documentation and contributor

CONTRIBUTORS.md

@@ -18,5 +18,6 @@
 # Contributors
 
 - **[Victor Salimonov](https://github.com/VikTorSalimonov)**
+- **[Sebastián Yonekura](https://github.com/syonekura)**
 
   * Documentation, screencasts

cvat/scripts/pascal_voc.py

@@ -6,6 +6,15 @@ from pascal_voc_writer import Writer
 
 
 def process_cvat_xml(xml_file, img_dir, annotation_dir):
+    """
+    Transforms a single XML in CVAT format to multiple PASCAL VOC format
+    XMls.
+
+    :param xml_file: CVAT format XML
+    :param img_dir: image directory of the dataset
+    :param annotation_dir: directory of annotations with PASCAL VOC format
+    :return:
+    """
     os.makedirs(annotation_dir)
     cvat_xml = xml.etree.ElementTree.parse(xml_file)
 
@@ -33,9 +42,10 @@ def process_cvat_xml(xml_file, img_dir, annotation_dir):
 
 parser = argparse.ArgumentParser(description='Transforms CVAT XML to Pascal '
                                              'VOC format')
-parser.add_argument('cvat_xml', type=argparse.FileType())
-parser.add_argument('img_dir')
-parser.add_argument('annotation_dir')
+parser.add_argument('cvat_xml', type=argparse.FileType(), help='CVAT XML file')
+parser.add_argument('img_dir', help='Image directory of the dataset')
+parser.add_argument('annotation_dir', help='Output directory of '
+                                           'XML annotations')
 
 if __name__ == '__main__':
     args = vars(parser.parse_args())