Docs updates for E/A#97516 From/To filter narrows to workspace members

[MelvinBot]

Why this docs update

Expensify/App#97516 changes the Spend page From and To filters so that, when a Workspace filter is applied, they show only the members of the selected workspace instead of every contact you've ever shared an expense, report, or chat with. Users who were already selected stay in the list so they can still be deselected.

This behavior wasn't documented on the help site, so this PR adds a short section to the Spend page article explaining it.

What changed

docs/articles/new-expensify/reports-and-expenses/Getting-Started-with-the-Spend-Page.md

• Added a ## How the From and To filters narrow to workspace members section under Filters.
• Added related keywords (From filter, To filter, workspace filter, workspace members) for search retrieval.

Verification

• Verified filter labels against the current web UI: the Filters button and the From / To filter categories match. The Workspace filter appears when the account belongs to at least one workspace.
• Followed HELP_AUTHORING_GUIDELINES.md, HELPSITE_NAMING_CONVENTIONS.md, and TEMPLATE.md (task-based heading, bolded UI labels, no new # heading).

@bernhardoj, please review the files changed and confirm they reflect the current behavior. Then post a new comment saying @MelvinBot mark this PR as ready for review.

[MelvinBot]

The only failing check is Check independent approval — every other check (check, dryRun, spellcheck, validate, verify, verifySignedCommits, CLA) is passing.

There's nothing to fix in code here. Check independent approval isn't a test or lint failure — it's an approval gate that stays red until someone other than the PR author approves the PR. It clears on its own once this docs change gets an independent review/approval.

So no push is needed. Please review the file change and, if it looks good, get it approved (or reply @MelvinBot mark this PR as ready for review per the PR description) — the check will go green after that.