docs: comprehensive documentation for HAN-387

- README.md: full project overview, installation, quick start, CLI reference,
  output format descriptions, architecture overview, and dnstraverse comparison
- GoDoc: package-level documentation for traverse, dns, config, output, and
  fingerprint packages
- GoDoc: TraverserConfig and TraversalResult type comments in traverser.go

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: multica-agent <github@multica.ai>

internal/dns/query.go

@@ -1,3 +1,9 @@
+// Package dns provides the low-level DNS query primitives used by ExploreDNS.
+//
+// It wraps the github.com/miekg/dns library to provide retrying, TCP fallback,
+// EDNS0 buffer size negotiation, and root server discovery.  The package is
+// intentionally narrow: it sends iterative (non-recursive) queries and returns
+// the raw responses for the traversal engine to interpret.
 package dns
 
 import (