Standardize heading capitalization to sentence case

[mintlify]

Summary

Audited all 50+ MDX documentation pages for writing style and tone consistency. The predominant style across newer pages (webhooks section, holds-and-fees, container-statuses, SDK docs, dashboard-deep-linking) uses sentence case for headings, but many older pages used Title Case inconsistently.

This PR standardizes all headings to sentence case across 20 files, preserving proper nouns (Terminal49, DataSync), acronyms (API, URL, JSON, MCP, SDK), and technical terms.

Files changed

• Getting Started (4 files): start-here, tracking-shipments-and-containers, list-shipments-and-containers, receive-status-updates
• In-Depth Guides (9 files): quickstart, tracking-request-lifecycle, container-statuses, event-timestamps, auto-detect-carrier, rail-integration-guide, routing, rate-limiting, webhooks, mcp, document-processing-workflows, terminal49-widget
• Useful Info (2 files): api-data-sources-availability, test-numbers
• DataSync (1 file): overview
• MCP (1 file): home

What was not changed

• Technical content, code samples, and API references were left untouched
• Component titles (Accordion, Card, Tab) were not modified
• Proper nouns and acronyms remain capitalized
• Pages that were already consistent (webhook use cases, SDK docs, holds-and-fees, dashboard-deep-linking) required no changes

Also fixed "Terminal 49" → "Terminal49" in api-data-sources-availability.mdx.

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Project	Status	Preview	Updated (UTC)
terminal49	🟢 Ready	View Preview	Apr 13, 2026, 12:32 AM

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Project	Deployment	Actions	Updated (UTC)
api	Building	Preview, Comment	Apr 13, 2026 0:31am