docs: update 3-2-inviting-removing-users.md

[habib424]

Drafted by Ship Ship 🚢 — confidence 🟢 high

What changed

Added a new subsection "Controlling Welcome Emails" that explains the organization-wide toggle in Organization Settings > User emails and the per-user "Send welcome email" override toggle in the user create/edit dialog. This helps admins understand when users receive onboarding emails and how to control that behavior.

Source PRs

• axolotl#4139 — feat: add user welcome email toggles

How to use this PR

1. Review the diff against the existing article — focus on accuracy and customer voice.
2. Merge if it reads well. Edit and push to this branch if it needs adjustment.
3. Close without merging if the article doesn't actually need this update.

Once we have a track record of clean drafts, we'll graduate to auto-merge with a delay buffer. For now: human-in-the-loop.