[UserGuide] Automate handling of downloaded .md translations

[imnasnainaec]

There are several modifications necessary to .md files downloaded from Crowdin (translations of our User Guide files). Some of them have been automated with tools in Crowdin, but one big one remains: some, but not all, of the images are localized, and for those that are localized, the url within the file needs to be changed from .png to .[es/zh].png.

Options:

• Duplicate the non-localized images as if they were localized and add them to the repo.
• Write a script to make those updates depending on whether the localized file is available.
• Have a User Guide pre-build/serve step that duplicates the non-localized images temporarily.

The third is preferable if not too complicated.