Replace `@@snip` example involving build tool dependency declaration

[metasim]

With the new @@dependency directive, probably shouldn't use the long form version of declaring dependency constructs as an acceptable example of grouped @@snips.

http://developer.lightbend.com/docs/paradox/latest/features/snippet-inclusion.html#snip-block

[raboof]

Good idea, would you be up for creating a PR?