added documentation for the new cookiejar Request.meta key

docs/topics/downloader-middleware.rst

@@ -178,6 +178,22 @@ The following settings can be used to configure the cookie middleware:
 * :setting:`COOKIES_ENABLED`
 * :setting:`COOKIES_DEBUG`
 
+.. reqmeta:: cookiejar
+
+Multiple cookie sessions per spider
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. versionadded:: 0.15
+
+There is support for keeping multiple cookie sessions per spider by using the
+:reqmeta:`cookiejar` Request meta key. By default it uses a single cookie jar
+(session), but you can pass an identifier to use different ones.
+
+For example::
+
+    for i, url in enumerate(urls):
+        return Request("http://www.example.com", meta={'cookiejar': i})
+
 .. setting:: COOKIES_ENABLED
 
 COOKIES_ENABLED

docs/topics/request-response.rst

@@ -210,6 +210,7 @@ Those are:
 * :reqmeta:`dont_retry`
 * :reqmeta:`handle_httpstatus_list`
 * ``dont_merge_cookies`` (see ``cookies`` parameter of :class:`Request` constructor)
+* :reqmeta:`cookiejar`
 * :reqmeta:`redirect_urls`
 
 .. _topics-request-response-ref-request-subclasses: