Update API docs for database import

API.md

@@ -2561,6 +2561,8 @@ Import a Tautulli, PlexWatch, or Plexivity database into Tautulli.
 ```
 Required parameters:
     app (str):                      "tautulli" or "plexwatch" or "plexivity"
+    database_file (file):           The database file to import (multipart/form-data)
+    or
     database_path (str):            The full path to the plexwatch database file
     method (str):                   For Tautulli only, "merge" or "overwrite"
     table_name (str):               For PlexWatch or Plexivity only, "processed" or "grouped"
@@ -2573,7 +2575,10 @@ Optional parameters:
                                     of seconds for a stream to import
 
 Returns:
-    None
+    json:
+        {"result": "success",
+         "message": "Import has started. Check the logs to monitor any problems."
+         }
 ```