secure password storage; documentation

 To store passwords securely, they should be salted, then hashed with a
 slow hash function. This library uses PBKDF1-SHA256, and handles all
 the details. It uses the cryptohash package for speed; if you need a
 pure Haskell library, pwstore-purehaskell has the exact same API, but
 uses only pure Haskell. It is about 25 times slower than this package,
 but still quite usable.
 .
 This package provides the documentation for a library for the Haskell
 programming language.
 See http://www.haskell.org/ for more information on Haskell.