[No QA] Update help docs for Release 1: Workspace Rooms directory

[MelvinBot]

Explanation of Change

Documents the new Workspace Rooms directory on ExpensifyHelp as part of the resource updates for the Workspace Rooms project (Expensify/Expensify#650290, tracking Expensify/App#85043).

The Workspace Rooms directory adds a predictable way to find a workspace's rooms (reachable from Workspaces > [Workspace] > Rooms, under Members) so people no longer have to rely on pinning to find a room such as the policy expense chat. Rather than introduce a new article for a discovery/navigation enhancement, this updates the existing Create-a-New-Chat.md article, which already explains what rooms are and how to create them. Two new task-based sections were added:

• How to find rooms in a workspace – where the directory lives, what each row shows (icon, name, who created it, member count), alphabetical ordering, the search bar threshold, the admin-vs-member click behavior, and that opening a room from the directory does not auto-join you.
• How to create a room from a workspace – creating a room via the Create button in the directory, with the new room highlighted on return.

A keyword update (workspace rooms, rooms directory) was added to the frontmatter for retrieval.

This covers the single release scoped for this project (there are no phased UI releases), so all help-site changes are in this one PR.

Fixed Issues

$ https://github.com/Expensify/Expensify/issues/650290
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.

• Verify that no errors appear in the JS console

Offline tests

N/A — documentation-only change.

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

Screenshots/Videos

Documentation-only change; the article includes a non-rendered screenshot placeholder for the reviewer to capture the Rooms directory once the feature ships.

[OSBotify]

A preview of your ExpensifyHelp changes have been deployed to https://22f95d53.helpdot.pages.dev ⚡️

Updated articles:

• articles/new-expensify/chat/Create-a-New-Chat

[stephanieelliott]

Closing in favor of #93992