[Docs] Clarify automation setup without a default destination

[roomote-community]

​Opened on behalf of @mrubens. Follow up by mentioning @roomote, in the web UI, or in Discord.

What changed

• clarify that Suggest Ideas and Summarize Merged PRs can be configured before a shared Automation output destination exists
• direct administrators to choose an explicit destination in each automation's setup dialog

Why this change was made

The daily public-documentation audit reviewed all eight first-parent commits merged into develop during the exact window from 2026-09-20T03:00:45.952Z through 2026-09-21T03:00:45.952Z. The shipped UI no longer requires a shared automation destination for these two setup flows, but the public docs still instructed administrators to configure it first.

Impact

Administrators now get setup guidance that matches the current automation UI without duplicating the broader destination terminology changes in open documentation work. This is a documentation-only change; the repository-prescribed Mintlify validation and broken-link checks, git diff --check, and the pre-push static checks passed.

[roomote-community]

No code issues found. See task

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