Add internal Billing & Subscriptions topic index for help authors

[MelvinBot]

Explanation of Change

Adds a new internal reference file, docs/topic-index.md, that maps commonly referenced New Expensify Billing & Subscriptions topics to their canonical article + section anchor.

This index is for help content authors, not members — it is intentionally placed at the docs/ root (not under docs/articles/), so it is not a routed, published help article. Its purpose is to give authors one canonical place to link whenever a topic (a role, definition, setting, eligibility rule, or workflow) is referenced from another article, instead of re-explaining it.

What it contains:

• A grouped table (Roles & permissions, Members, Plans, Subscriptions, Annual subscription settings, Pricing, Billing tasks & receipts) of ~30 topics, each with the exact article path, the most specific section anchor, and a brief description of what that section covers.
• Common aliases in the Topic column where helpful (e.g. Workspace owner / billing owner).
• A final ## Gaps section for topics that are referenced across articles but lack a clear canonical home in this folder (deleting a workspace to stop billing, invoiced subscriptions, free trial).

No existing articles were modified and no new member-facing content was created.

Every article path and heading anchor was validated against the actual headings in docs/articles/new-expensify/billing-and-subscriptions/, and the anchor style (kramdown: lowercase, spaces → hyphens, punctuation stripped) matches the existing cross-article links already used in the repo (e.g. #what-is-a-workspace-owner).

Fixed Issues

$ https://github.com/Expensify/Expensify/issues/661288
PROPOSAL:

Tests

// TODO: The human co-author must fill out the tests you ran before marking this PR as "ready for review"
// Please describe what tests you performed that validates your changed worked.

This PR adds a single non-routed internal Markdown file (docs/topic-index.md). It is not a published help article and does not affect app code, docs routing, or the JS console. Suggested review check: open the file and spot-check that the linked article paths + anchors resolve to the intended sections.

• Verify that no errors appear in the JS console

Offline tests

N/A — internal documentation file only.

QA Steps

// TODO: The human co-author must fill out the QA tests you ran before marking this PR as "ready for review".
// Please describe what QA needs to do to validate your changes and what areas do they need to test for regressions.

• Verify that no errors appear in the JS console

PR Author Checklist

• I linked the correct issue in the ### Fixed Issues section above
• I wrote clear testing steps that cover the changes made in this PR
  • I added steps for local testing in the Tests section
  • I added steps for the expected offline behavior in the Offline steps section
  • I added steps for Staging and/or Production testing in the QA steps section
  • I added steps to cover failure scenarios (i.e. verify an input displays the correct error message if the entered data is not correct)
  • I turned off my network connection and tested it while offline to ensure it matches the expected behavior (i.e. verify the default avatar icon is displayed if app is offline)
  • I tested this PR with a High Traffic account against the staging or production API to ensure there are no regressions (e.g. long loading states that impact usability).
• I included screenshots or videos for tests on all platforms
• I ran the tests on all platforms & verified they passed on:
  • Android: Native
  • Android: mWeb Chrome
  • iOS: Native
  • iOS: mWeb Safari
  • MacOS: Chrome / Safari
• I verified there are no console errors (if there's a console error not related to the PR, report it or open an issue for it to be fixed)
• I followed proper code patterns (see Reviewing the code)
  • I verified that comments were added to code that is not self explanatory
  • I verified that any new or modified comments were clear, correct English, and explained "why" the code was doing something instead of only explaining "what" the code was doing.
  • I verified any copy / text that was added to the app is grammatically correct in English. It adheres to proper capitalization guidelines (note: only the first word of header/labels should be capitalized), and is either coming verbatim from figma or has been approved by marketing (in order to get marketing approval, ask the Bug Zero team member to add the Waiting for copy label to the issue)
• If a new code pattern is added I verified it was agreed to be used by multiple Expensify engineers
• I followed the guidelines as stated in the Review Guidelines
• I tested other components that can be impacted by my changes (i.e. if the PR modifies a shared library or component like Avatar, I verified the components using Avatar are working as expected)
• If a new CSS style is added I verified that:
  • A similar style doesn't already exist
  • The style can't be created with an existing StyleUtils function (i.e. StyleUtils.getBackgroundAndBorderStyle(theme.componentBG))
• If new assets were added or existing ones were modified, I verified that:
  • The assets are optimized and compressed (for SVG files, run npm run compress-svg)
  • The assets load correctly across all supported platforms.
• If the PR modifies code that runs when editing or sending messages, I tested and verified there is no unexpected behavior for all supported markdown - URLs, single line code, code blocks, quotes, headings, bold, strikethrough, and italic.
• If the PR modifies a generic component, I tested and verified that those changes do not break usages of that component in the rest of the App (i.e. if a shared library or component like Avatar is modified, I verified that Avatar is working as expected in all cases)
• If the PR modifies a component related to any of the existing Storybook stories, I tested and verified all stories for that component are still working as expected.
• If the PR modifies a component or page that can be accessed by a direct deeplink, I verified that the code functions as expected when the deeplink is used - from a logged in and logged out account.
• If the PR modifies the UI (e.g. new buttons, new UI components, changing the padding/spacing/sizing, moving components, etc) or modifies the form input styles:
  • I verified that all the inputs inside a form are aligned with each other.
  • I added Design label and/or tagged @Expensify/design so the design team can review the changes.
• I added unit tests for any new feature or bug fix in this PR to help automatically prevent regressions in this user flow.
• If the main branch was merged into this PR after a review, I tested again and verified the outcome was still expected according to the Test steps.

Screenshots/Videos

Android: Native

Android: mWeb Chrome

iOS: Native

iOS: mWeb Safari

MacOS: Chrome / Safari

[OSBotify]

A preview of your ExpensifyHelp changes have been deployed to https://62ead47f.helpdot.pages.dev ⚡️

Updated articles:

• topic-index

[MelvinBot]

The only failing check is PR Author Checklist / checklist — every other check (build, verify, validate, spellcheck, dryRun, CLA, verifySignedCommits) is passing. ✅

That check isn't a code failure. It fails because the author checklist boxes are unchecked:

You completed 0 out of 38 checklist items with 38 unfinished items
##[error] PR Author Checklist is not completely filled out.

There's nothing in the code to fix or push here — the checklist is meant to be completed by the human author/co-author, and I don't check those boxes on anyone's behalf. Once you (as the co-author) review the changes, fill out the Tests / QA Steps sections, and check off the applicable items in the PR Author Checklist, that check will pass.