Update help docs for Mark as done copy

[MelvinBot]

Summary

• Adds notes to three New Expensify help articles explaining that track-intent users (those who selected "Track and budget expenses" during onboarding) on workspaces without approval workflows will see Mark as done instead of Submit/Approve, and marked as done instead of submitted in activity messages.
• Related to Update CTA and workspace chat copy for track-intent users #86460 which introduced the "Mark as done" copy for track-intent users.

Articles updated:

1. Create-and-Submit-Reports.md — Added note about alternative button text and activity message in the submit section, and updated the FAQ about the missing Submit button.
2. Understanding-Report-Statuses-and-Actions.md — Added note under context-specific buttons explaining the alternative labels.
3. Expense-and-Report-Actions.md — Added note under primary actions table explaining the alternative labels.

Test plan

• Verify the three updated articles render correctly on the help site
• Confirm the notes accurately describe the behavior introduced in Update CTA and workspace chat copy for track-intent users #86460
• Check that all formatting follows HELPSITE_NAMING_CONVENTIONS.md and HELP_AUTHORING_GUIDELINES.md

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[chatgpt-codex-connector]

Move the onboarding note outside the primary actions table

The inserted **Note:** line sits between Approve and Pay table rows, which breaks Markdown table continuity; in GFM/CommonMark-style renderers this ends the table and causes subsequent | **Pay** | ... rows to render as plain text instead of table entries. In the help article, that will hide or misformat key primary actions for readers.

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