Clarify service properties usage limitations

[GabrielCW]

Hi there,

Referring to these guide pages, I have attempted to use services' properties as a basis for a controller's queryParams: Accessing services and Specifying query parameters.

I was getting outdated service values in my queryParams and couldn't understand why (for reference, here's my twiddle). With help from @luxferresum on Slack, we were able to trace it back to an existing issue: emberjs/ember.js#9819

To avoid other people encountering the same problem, it might be good to add a section about known limitations of services in relation to queryParams.
Maybe a small warning paragraph about how some computed properties can't be used with queryParams would be appropriate.