feature: @DgsData should be @Repeatable

[xenoterracide]

https://netflix.github.io/dgs/datafetching/#multiple-dgsdata-annotations-via-dgsdatalist

@DgsData.List({
    @DgsData(parentType = "Query", field = "movies"),
    @DgsData(parentType = "Query", field = "shows")
})

couldn't @DgsData have @Repeatable?

[detinho]

It seems it already is a repeating annotation.

Opened a PR Netflix/dgs#121 to update the docs.