Add Resource Collection example to Everything server

[cliffhall]

Is your feature request related to a problem? Please describe.
@olaservo suggested that we add an example of resource collections. It was prompted by this discussion on the topic.

Describe the solution you'd like
@olaservo has posted a gist that demonstrates the pattern where a single resources/read request

Her example returns multiple ResourceContents with different URIs - useful for modeling collections, indexes, or composite resources.

Resources like the following:

• • demo://collection/summer-specials: Returns all items as separate resources
• • demo://collection/by-category/{category}: Returns items filtered by category
• • demo://collection/item/{id}: Returns a single item (for individual access)

Describe alternatives you've considered
None really. This is a well thought out example, and I think we should add it when the newly refactored Everything server PR is merged.