Add xerxes-project and osint-recon (Discovery)

[JMarchiori13]

Adds two Rust tools to the Discovery section, matching the list's entry style:

• xerxes-project — modular pentest harness in Rust: plugin architecture, async TCP port scanner, subdomain brute-forcer (DoH + wildcard filtering), web fuzzer, Shodan integration, HTTP Basic credential testing. Dry-run mode and confirmation gates for destructive actions. For authorized assessments.
• osint-recon — passive OSINT reconnaissance framework in Rust: subdomains (crt.sh), DNS-over-HTTPS, ASN/netblocks, certificate transparency history, GitHub dorking, tech fingerprinting, Brazilian context (CNPJ/CEP). Passive sources only, no scanning.

Both are actively maintained, MIT licensed, CI-tested, with prebuilt binaries for Windows/Linux/macOS. Thanks for maintaining this list!