docs: add address resolver how-to guide (PHP, C#)

[Aryex]

Summary

Add documentation for the address resolver feature across PHP and C# clients.

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

Source Commits

• 8f00aae — feat: add address resolver support for standalone and cluster clients.
• 7a822d4 — Support custom socket address resolution (#392)

Changes

• Added new how-to page: how-to/connections/address-resolver.mdx
• Covers basic usage, fallback behavior, and cluster client usage
• PHP examples for ValkeyGlide and ValkeyGlideCluster
• C# examples using StandaloneClientConfigurationBuilder / ClusterClientConfigurationBuilder with WithAddressResolver()
• Language-specific notes (PHP: MSHUTDOWN/RSHUTDOWN cleanup; C#: thread-safety, 1024-byte hostname limit, internal GC pin)

Context

Php #196 adds a custom address resolver callback to both standalone and cluster PHP clients. C# #392 ports the same feature to the C# client using AddressResolverDelegate and the WithAddressResolver() builder method.

The resolver intercepts host/port resolution at connection time, enabling DNS overrides, service mesh scenarios, and testing with fake addresses. If the resolver throws or returns invalid data, the client gracefully falls back to the original address.

cc @affonsov

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This PR was generated by the automated documentation pipeline.

[Aryex]

📝 Updated PR description with 7a822d4 — Support custom socket address resolution (#392)

Added C# code examples to the address resolver how-to page covering basic usage, fallback behavior, and cluster client configuration.