Consider moving expected location of yml files to a subdir of assets

[brendanhoar]

I'd like to have a single directory tree for infinity grid yml configs across multiple sd-webui installs.

One way to do this is to create directory links to a single directory elsewhere that can then be used by multiple installs.

As it is now, the yml files are intermixed with other assets in the extension's subtree, and I'm not sure it's a good idea to share the assets directory between sd-webui installs (that might have different versions/configs of the extension).

Thanks for your consideration.