cleanup, docs

site/doc/pages/sha256.txt

@@ -1,10 +1,17 @@
-# sha256
+:sig
+String sha256(String data)
 
+:params
+data : bytes to hash
+return value : the raw 32-byte SHA-256 digest
 
-Returns the raw 32-byte SHA-256 digest for `data`. Use `sha256_hex()` for printable lowercase hex.
+:content
+Returns the SHA-256 digest of `data` as raw bytes. Prefer `sha256_hex()` when you need printable text; use the raw form when feeding the digest into other binary operations.
 
 :example
-print(sha256("hello").length(), "\n");
+print(sha256("abc").length(), " raw bytes, hex = ", sha256_hex("abc"), "\n");
 
 :see
->noise
+>sys
+sha256_hex
+hmac_sha256