[Bf-docboard] Translation update_po utility

[Campbell Barton]

Hi,
guys doing translations may be interested to know theres now a utility
to update translations.

It just runs the commands to update PO files as documented, but is
less trouble then doing manually.
This uses bash so am afraid its not so handy on ms-windows.
On the other hand, I run this regularly, (at least weekly).
So it isn't essential for translators to use either.

To update PO files, run:

  make update_po

... or you can execute the script directly, see:
https://developer.blender.org/diffusion/BM/browse/trunk/blender_docs/tools/maintenance/update_po.sh

-- 
- Campbell