[No QA] Docs updates for E/A#95875 Suggested tab in agent rule creation

[MelvinBot]

Explanation of Change

Follow-up help site update for the agent rule creation changes in #95875, which adds a Suggested tab (with a Find a rule search and AI-generated suggestions) and an Edit tab to the "Add agent rule" flow.

Updated docs/articles/new-expensify/ai-agents/Create-Agent-Rules.md:

• Rewrote the How to create an Agent rule steps to reflect the new two-tab flow: the Suggested tab opens first, you can pick a suggestion and click Next to prefill the Edit tab, or open the Edit tab to write your own rule, then Save.
• Documented the empty state (No suggestions available) shown when no suggestions are available (e.g. offline).
• Corrected the button label from Add AI rule to Add agent rule to match the live UI.

All UI labels (Add agent rule, Suggested, Edit, Find a rule, Next, Save, No suggestions available) were verified against the strings added in the source PR and follow HELPSITE_NAMING_CONVENTIONS.md.

Fixed Issues

Related to #95875

@samranahm, please review the files changed and confirm they reflect the current behavior. Then mark this PR Ready for review.

[OSBotify]

A preview of your ExpensifyHelp changes have been deployed to https://21cc3cca.helpdot.pages.dev ⚡️

Updated articles:

• articles/new-expensify/ai-agents/Create-Agent-Rules