Restructure folders and attachments to check for orphaned resources

[bparks13]

DocLinkChecker has a feature that allows it to check if any resources are orphaned (i.e., not used in the docs). However, it does not currently work due to our folder hierarchy / naming convention. To rectify this, we can move all images to an '.attachments' folder (this is the recommended hierarchy for docs management by Docfx and DocLinkChecker). Then, we can add '.attachments' to the ResourceFolderNames argument of the DocLinkChecker.config file.

There are some additional steps that might be necessary, such as moving the *-operator.svg files into a specific subfolder that is not checked at this time. The reason being that DocLinkChecker operates on the raw *.md files, and does not check the HTML files, but the operator SVG images are only placed into the HTML pages after running through the templating process.

While doing this, it would make sense to organize the images into specific subfolders to make it easier to browse and find specific images.

[jonnew]

I don't think this is a huge deal. Also, I'm know, esp in docs repos, to place content in there that might be useful in future. So, lets put it in the wishlist for now.