[Docs RFC] Add a note to caggs docs about when the time window closes

[Loquacity]

Describe change in content, appearance, or functionality

Seems like that there are situations where creating the CAGG (with data) may close the current time window even though the window isn’t over yet

Subject matter expert (SME)

[If known, who is a good person to ask about this topic]

Deadline

[When does this need to be addressed]

Any further info

Community Slack thread: https://timescaledb.slack.com/archives/C4GT3N90X/p1672668498951599?thread_ts=1672571286.532699&cid=C4GT3N90X

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