TASK-86684: Adding dns_max_udp_queries_per_port to documentation

[dkoerichbird]

Note

Adds documentation for new DNS tuning option and references it in indexes.

• New reference page content/momentum/4/config/ref-dns-max-udp-queries-per-port.md describing dns_max_udp_queries_per_port, including synopsis, description, default (0), and scope (global)
• Inserts dns_max_udp_queries_per_port into config-options-summary.md (Version: 5.2+, Type: sending, Default: 0, Scope: global)
• Adds the option to config/index.md listing with a short description

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