Add function example for response paging

Demonstrates how customer need to use the state when there is paging in response.

There are two ways to do it

- Store timestamp and page in state and in the next request start from the page stored in state
- Directly store the `next page url` in state and use it in next function invocation

See conversation in https://fivetran.slack.com/archives/C4J90DAS3/p1541029066058800