Image updates

[KevinGDialpad]

After #21#69, an image is updated the first time it's encountered, but it's never updated. The best way to update it is to do it manually from Confluence.

Investigate ways to update images automatically:

• When the document is updated, maybe check when the image was last updated if that's possible, and re-upload it if it has changed
  • Simpler: update the image attachment if the image file was modified in the same commit
• How to handle cases where the image is updated, but the document is not?

Another way is to re-think this image upload thing entirely and instead use links to raw.githubusercontent.com.

[KevinGDialpad]

Another way is to re-think this image upload thing entirely and instead use links to raw.githubusercontent.com.

Hm, probably not, since such links need to be authenticated. We can't put an auth token in the URL because A- the token can change and invalidate all the links and B- it's not great to just give a plain-text token to Confluence. There are probably other ways to authenticate a request to raw.githubusercontent.com, and maybe one of them will work on Confluence.