formatting and secret_key explanation

cookbook/sessions.md

@@ -66,10 +66,10 @@ Options related to sessions can be modified using the `sessions_parameters` dict
     web.config.session_parameters['secret_key'] = 'fLjUfxqXtfNoIldA0A0J'
     web.config.session_parameters['expired_message'] = 'Session expired'
 
- * cookie_name - name of the cookie used to store the session id
- * cookie_domain - domain for the cookie used to store the session id
- * timeout - number of second of inactivity that is allowed before the session expires
- * ignore_expiry - if true, the session timeout is ignored
- * ignore_change_ip - if false, the session is only valid when it is accessed from the same ip address that created the session
- * secret_key       - *requires explanation*
- * expired_message  - message displayed when the session expires
+ * `cookie_name` - name of the cookie used to store the session id
+ * `cookie_domain` - domain for the cookie used to store the session id
+ * `timeout` - number of second of inactivity that is allowed before the session expires
+ * `ignore_expiry` - if `True`, the session timeout is ignored
+ * `ignore_change_ip` - if `False`, the session is only valid when it is accessed from the same ip address that created the session
+ * `secret_key`       - salt used in session id hash generation (requires more explanation?  perhaps a link?)
+ * `expired_message`  - message displayed when the session expires