docs: Add PHP Error Tracking installation page

[inkeep]

Summary

Adds PHP to the Error Tracking installation documentation.

Changes

• Created contents/docs/error-tracking/installation/php.mdx with step-by-step installation instructions
• Added PHP to the error tracking installation sidebar navigation in src/navs/index.js

Details

This PR adds error tracking documentation for the PHP SDK, following the feature introduced in PostHog/posthog-php#109.

Key points covered:

• SDK installation via Composer
• Client initialization with API key and host
• Manual exception capture using PostHog::captureException()
• Including additional context properties with exceptions
• Verification step

The page follows the same pattern as the Go and Elixir installation pages (inline steps using the <Steps> component) since PHP uses manual exception capture rather than automatic capture.

Since the installation platforms grid uses usePlatformList to dynamically generate from MDX files with platformLogo frontmatter, PHP will automatically appear in the installation grid at /docs/error-tracking/installation.

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This PR was created by the Inkeep Content Writer agent, which is maintained by the Docs and Wizard team. Please reach out on Slack for help if needed.

Note: Since I cannot access the posthog-php repository directly to verify exact API signatures, please review the captureException() method signature to ensure it matches the actual implementation.

[github-actions]

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[github-actions]

Deploy preview

Status	Details	Updated (UTC)
🟢 Ready	View preview	Apr 07, 2026 05:12PM

[github-actions]

Vale prose linter → found 0 errors, 23 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/error-tracking/installation/php.mdx — 0 errors, 3 warnings, 0 suggestions

Line	Severity	Message	Rule
3:15	warning	Use 'PHP' instead of 'php'.	Vale.Terms
152:53	warning	Capitalize 'Error Tracking' for PostHog's product. Use 'error tracking' for the general industry concept.	PostHogBase.ProductNames
154:59	warning	'Throwable' is a possible misspelling.	PostHogBase.Spelling

contents/docs/libraries/php/index.mdx — 0 errors, 20 warnings, 0 suggestions

Line	Severity	Message	Rule
6:18	warning	Use 'GitHub' instead of 'github'.	Vale.Terms
6:37	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
6:45	warning	Use 'PHP' instead of 'php'.	Vale.Terms
86:4	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'Feature flags' for the general industry concept.	PostHogBase.ProductNames
86:4	warning	'Feature flags' heading should be in sentence case, and product names should be capitalized.	PostHogBase.SentenceCase
106:8	warning	Capitalize 'Experiments' for PostHog's product. Use 'experiments' for the general industry concept.	PostHogBase.ProductNames
106:51	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
106:124	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
116:28	warning	Capitalize 'Experiments' for PostHog's product. Use 'experiments' for the general industry concept.	PostHogBase.ProductNames
116:54	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
120:122	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
120:130	warning	Use 'PHP' instead of 'php'.	Vale.Terms
146:4	warning	Capitalize 'Error Tracking' for PostHog's product. Use 'Error tracking' for the general industry concept.	PostHogBase.ProductNames
146:4	warning	'Error tracking' heading should be in sentence case, and product names should be capitalized.	PostHogBase.SentenceCase
148:73	warning	Capitalize 'Error Tracking' for PostHog's product. Use 'error tracking' for the general industry concept.	PostHogBase.ProductNames
166:115	warning	Capitalize 'Error Tracking' for PostHog's product. Use 'error tracking' for the general industry concept.	PostHogBase.ProductNames
192:110	warning	Capitalize 'Feature Flags' for PostHog's product. Use 'feature flags' for the general industry concept.	PostHogBase.ProductNames
194:276	warning	Use 'PHP' instead of 'php'.	Vale.Terms
195:78	warning	Capitalize 'Logs' for PostHog's product. Use 'logs' for the general industry concept.	PostHogBase.ProductNames
196:87	warning	Capitalize 'Error Tracking' for PostHog's product. Use 'error tracking' for the general industry concept.	PostHogBase.ProductNames