Document new "continuedl" FileDownloader option

diff --git a/youtube-dl b/youtube-dl
index 06ba25d..6730898 100755 (executable)
--- a/youtube-dl
+++ b/youtube-dl
@@ -114,6 +114,7 @@ class FileDownloader(object):
        ignoreerrors:   Do not stop on download errors.
        ratelimit:      Download speed limit, in bytes/sec.
        nooverwrites:   Prevent overwriting files.
+       continuedl:     Try to continue downloads if possible.
        """
 
        params = None