slhdsa: supplements package level document

Author: emmansun

slhdsa/dsa.go

@@ -2,6 +2,11 @@
 // Use of this source code is governed by a MIT-style
 // license that can be found in the LICENSE file.
 
+// Package slhdsa implements the quantum-resistant stateless hash-based digital signature standard 
+// SLH-DSA (based on SPHINCS+), as specified in [NIST FIPS 205].
+//
+// [NIST FIPS 205]: https://doi.org/10.6028/NIST.FIPS.205
+//
 //go:build go1.24
 
 package slhdsa