[No QA] Docs updates for E/A#94696 Rules Revamp hub tabs and new rule types

[MelvinBot]

Summary

Updates the Help site article Workspace-Rules.md to reflect the revamped Rules hub introduced in #94696 (Rules Revamp — Release 2).

What changed in the docs

• Added How the Rules hub is organized describing the five tabs: General, Card restrictions, Expense defaults, Require fields, and Flag for review.
• Added How to create a rule in the Rules hub covering the + Rule → New rule flow with its four options (Restrict card spend, Flag for review, Require fields, Apply expense defaults).
• Added How to configure Require fields rules and How to configure Flag for review rules for the two new category-based rule types.
• Added a note to How to configure Category Rules explaining that, under the updated experience, Flag amounts over and Require fields are now created in the Rules hub instead of individual category settings.
• Added a note near the top flagging that this is the updated Rules experience.

All feature, tab, and button labels were taken verbatim from the strings added in #94696 (src/languages/en.ts → workspace.rules), following docs/HELPSITE_NAMING_CONVENTIONS.md, docs/HELP_AUTHORING_GUIDELINES.md, and docs/TEMPLATE.md.

⚠️ Important: this feature is behind a beta

The revamped Rules hub is gated behind the rulesRevamp beta (CONST.BETAS.RULES_REVAMP) and is not yet GA. Most workspaces still see the pre-revamp Rules page. Please hold this PR until the rulesRevamp beta rolls out to everyone, and adjust the wording if the tabs/flow change before GA.

Notes / things to verify

• I kept the existing article's #-per-section heading style for consistency with the current file rather than reformatting it.
• Exact receipt-requirement toggle labels on the Require fields flow (e.g. Always require receipt vs Require itemized receipt and their amount thresholds) should be confirmed against the live UI.
• I did not rewrite the existing pre-revamp sections (Expense Rules, Spend rules, Prohibited Expenses, Expense Report rules) since those still describe the current GA behavior; they can be reorganized into the new tab structure once the beta is GA.

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@Krishna2323, 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://8e33f13a.helpdot.pages.dev ⚡️

Updated articles:

• articles/new-expensify/workspaces/Workspace-Rules