Add 2 warnings about potential path length issues

docs/administration.md

@@ -267,6 +267,12 @@ The filenames generated by this command follow the format
 paperless to use `PAPERLESS_FILENAME_FORMAT` for exported filenames
 instead, specify `--use-filename-format`.
 
+!!! warning
+
+    If exporting with the file name format, there may be errors due to
+    your operating system's maximum path lengths.  Try adjusting the export
+    target or consider not using the filename format.
+
 ### Document importer {#importer}
 
 The document importer takes the export produced by the [Document