Update README to include SHA-256 (#45)

Author: mattmook

cryptohash/README.md

@@ -63,7 +63,7 @@ The following algorithms are supported:
 - PANAMA
 - RadioGatun32, RadioGatun64
 - RIPEMD, RIPEMD-128, RIPEMD-160, RIPEMD-256, RIPEMD-320
-- SHA-0, SHA-1, SHA-224, SHA-384, SHA-512, SHA-512/224, SHA-512/256
+- SHA-0, SHA-1, SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, SHA-512/256
 - SHA3-224, SHA3-256, SHA3-384, SHA3-512
 - Shabal-192, Shabal-224, Shabal-256, Shabal-384, Shabal-512
 - SHAKE128, SHAKE256