docs: update Laravel PHP SDK guide

[marandaneto]

Changes

Updates the Laravel library docs to:

• Clarify that Laravel integrates through the PostHog PHP SDK and link to the PHP SDK docs for shared API details.
• Document environment variables and Laravel services config initialization.
• Add request context middleware for applying PostHog tracing headers from client SDKs such as PostHog JS, without including a frontend setup example.
• Add Laravel exception reporting guidance and a note about flushing in long-running processes.

Checklist

• I've read the docs and/or content style guides.
• Words are spelled using American English
• Use relative URLs for internal links
• I've checked the pages added or changed in the Vercel preview build
• If I moved a page, I added a redirect in vercel.json

[github-actions]

Deploy preview

Status	Details	Updated (UTC)
🟢 Ready	View preview	May 20, 2026 05:03PM

[github-actions]

Vale prose linter → found 0 errors, 5 warnings, 0 suggestions in your markdown

Full report → Copy the linter results into an LLM to batch-fix issues.

Linter being weird? Update the rules!

contents/docs/libraries/laravel.md — 0 errors, 5 warnings, 0 suggestions

Line	Severity	Message	Rule
3:15	warning	Use 'Laravel' instead of 'laravel'.	Vale.Terms
6:185	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
100:4	warning	'Error tracking in Laravel' heading should be in sentence case, and product names should be capitalized.	PostHogBase.SentenceCase
100:4	warning	Capitalize 'Error Tracking' for PostHog's product. Use 'Error tracking' for the general industry concept.	PostHogBase.ProductNames
102:23	warning	Capitalize 'Error Tracking' for PostHog's product. Use 'error tracking' for the general industry concept.	PostHogBase.ProductNames