RunQueryResponse should be an array

[lostbean]

Querying something on: https://firestore.googleapis.com/v1/projects/xxxxx/databases/(default)/documents:runQuery

returns this:

[ { "document": { "name": "projects/xxxxx/databases/(default)/documents/doc/000000000", "fields": { "lastUpdate": { ... } } ]

Which is a list of RunQueryResponses instead of the single one. I'm not sure if this patch is applied to the right place due the code generation but I couldn't figure out exactly where to do it. If someone can point me the correct direction, I'll update this PR.