docs: PHP getLastError/clearLastError methods

[Aryex]

Summary

Document the new getLastError() and clearLastError() methods on ValkeyGlide/ValkeyGlideCluster for PHPRedis compatibility.

⚠️ Attention: This PR was generated automatically. Verify that all relevant pages have been updated.

Source Commits

• c48c619 — PHP: Implement getLastError() and clearLastError() for PHPRedis compatibility (Update Supported Valkey Commands #221)

Changes

• Expanded the "Error Handling" section in the PHPRedis migration guide with a new subsection documenting getLastError() / clearLastError() methods
• Added method signature table, behavior description, and side-by-side code examples (PHPRedis vs Valkey GLIDE)
• Added notes about NOSCRIPT prefix preservation for framework compatibility
• Added migration checklist item for error introspection verification

Context

Php #221 adds PHPRedis-compatible error introspection methods that libraries like Symfony Lock depend on. Without these methods, clearLastError() calls in Symfony Lock's RedisStore::evaluate() caused fatal errors. The documentation update ensures migrating users know these methods are now available and behave identically to PHPRedis.

cc @tnucera

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This PR was generated by the automated documentation pipeline.