start/end types in `GetRowsOptions`

[GuillaumeCisco]

https://github.com/googleapis/nodejs-bigtable/blob/752a6e7b5864f627940904d8d85008ae3dd6046d/src/table.ts#L249

Looks like type is incorrect. It can be either a string or an object {value: string, inclusive: bool }

See examples: https://cloud.google.com/nodejs/docs/reference/bigtable/latest/bigtable/table

[danieljbruce]

Where do you see this in the examples?