add versionblocks to cumulative metrics doc

[mirnawong1]

this pr adds versionblocks (1.8 and lower, and 1.9+) to the cumulative metrics doc to differentiate the available parameters.

cumulative_type_params are only available in “versionless” for dbt-cloud users, which should be mentioned in the documentation.
If you’re a dbt-core user, not dbt-cloud, then you can still use the grain_to_date & window params, but nested under type_params instead of cumulative_type_params. The period_agg param is not available to dbt-core users yet.

raised in this internal slack thread and by user in dbt community: https://dbt-labs.slack.com/archives/C02NCQ9483C/p1724944680040759

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Name	Status	Preview	Updated (UTC)
docs-getdbt-com	✅ Ready (Inspect)	Visit Preview	Aug 29, 2024 4:27pm

[courtneyholcomb]

Left a couple of notes inline, but otherwise looks great! Thank you!