add kwargs docstring

Adds some info about the kwargs keywords.

Author: p-galligan

process_request/routines.py

@@ -196,6 +196,9 @@ def get_request_data(self, request_type, baseurl, **kwargs):
             request_type (str): string indicating whether the request is for the
             readingroom or duplication.
             baseurl (str): Base url for an ArchivesSpace instance.
+            **kwargs (dict): Includes varying Aeon request information depending
+                on the type of request. Also includes the below specified keys.
+                items (list): A list of ArchivesSpace archival object URIs.
 
         Returns:
             dict: Request data formatted for Aeon.