Fix: Notification channel navigation and email provider docs for IS 7.0.0 and 7.1.0

[Copilot]

Missing navigation entries and incorrect email provider doc paths for IS 7.0.0 and 7.1.0 notification channel guides.

Changes

• IS 7.0.0 mkdocs.yml: Changed nav title from Email & SMS → Notification Channels; updated email provider nav path to guides/notification-channels/configure-email-provider.md
• IS 7.1.0 mkdocs.yml: Updated email provider nav path to guides/notification-channels/configure-email-provider.md
• New files: Created guides/notification-channels/configure-email-provider.md wrapper for both 7.0.0 and 7.1.0 using the shared include pattern (matches 7.2.0/next)
• includes/.../configure-sms-provider.md: Conditional rendering — IS 7.0.0 renders "under the Email & SMS section"; all other versions render "under the Notification Channels section"
• includes/.../configure-email-provider.md: Same conditional applied to both console navigation references (**Notification Channels** > **Email Provider** → **Email & SMS** > **Email Provider** for IS 7.0.0)

Related PRs

Test environment

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