Added an additional link to NIST information on secure hashing.

This closes SF bug #458785.

Doc/lib/libsha.tex

@@ -75,4 +75,8 @@ substring.
      available online as plain text (at least one diagram was
      omitted) and as PDF at
      \url{http://csrc.nist.gov/publications/fips/fips180-1/fip180-1.pdf}.}
+
+  \seetitle[http://csrc.nist.gov/encryption/tkhash.html]
+           {Cryptographic Toolkit (Secure Hashing)}
+           {Links from NIST to various information on secure hashing.}
 \end{seealso}