Fix pep8 E302

Cf. http://legacy.python.org/dev/peps/pep-0008/#blank-lines

searx/engines/doku.py

@@ -27,6 +27,7 @@ search_url = '/?do=search'\
 # TODO             '&startRecord={offset}'\
 # TODO             '&maximumRecords={limit}'\
 
+
 # do search-request
 def request(query, params):