Clarify copyright status of misc/batch.py, synology.py

At the time these files were contributed there was no discussion
of the license that the authors wanted to use, but the project was
MIT licensed at the time. As such, these files deemed to be MIT licensed.

https://github.com/jbarlow83/OCRmyPDF/issues/600

debian/copyright

@@ -9,6 +9,11 @@ Copyright:
  (C) 2013-2016, 2015-2017 2016, 2017, 2017-2018, 2018 James R. Barlow
 License: GPL-3+
 
+Files: misc/*
+Copyright:
+ (C) 2020 James R. Barlow
+License: Expat
+
 Files: misc/completion/ocrmypdf.bash
 Copyright:
  (C) 2019 Frank Pille
@@ -20,6 +25,16 @@ Copyright:
  (C) 2020 James R. Barlow
 License: Expat
 
+Files: misc/batch.py
+Copyright:
+ (C) 2016 findingorder: https://github.com/findingorder
+License: Expat
+
+Files: misc/synology.py
+Copyright:
+ (C) github.com/Enantiomerie
+License: Expat
+
 Files: misc/watcher.py
 Copyright:
  (C) 2019 Ian Alexander: https://github.com/ianalexander