Added doc line in RegexLinkExtractor for the case when no allow/deny argument is given

--HG--
extra : convert_revision : svn%3Ab85faa78-f9eb-468e-a121-7cced6da292c%40584

scrapy/trunk/scrapy/link/extractors.py

@@ -36,6 +36,7 @@ class RegexLinkExtractor(LinkExtractor):
     Url matching is always performed against the absolute urls, never the
     relative urls found in pages.
 
+    If no allow/deny arguments are given, match all links.
     """
     
     def __init__(self, allow=(), deny=(), allow_domains=(), deny_domains=(), restrict_xpaths=(),