HHH-18892 document hash function support

Author: gavinking

documentation/src/main/asciidoc/querylanguage/Expressions.adoc

@@ -1174,8 +1174,8 @@ Finally, the following functions evaluate the id, version, or natural id of an e
 |===
 | Function | Purpose | JPA standard
 
-| `id()` | The value of the entity `@Id` attribute. | ✖
-| `version()` | The value of the entity `@Version` attribute. | ✖
+| `id()` | The value of the entity `@Id` attribute. | ✔
+| `version()` | The value of the entity `@Version` attribute. | ✔
 | `naturalid()` | The value of the entity `@NaturalId` attribute. | ✖
 | `fk()` | The value of the foreign key column mapped by a `@ManyToOne` (or logical `@OneToOne`) association.
 Useful with associations annotated `@NotFound`. | ✖
@@ -1207,6 +1207,23 @@ However, we note that the following language constructs work with arrays, and ar
 | `array includes subarray` | Determine if the elements of one array include all the elements of a second array
 |===
 
+[[functions-hash]]
+=== Hash functions
+
+The following functions work on most supported platforms:
+
+[[hash-functions]]
+[cols="12,~,^15"]
+|===
+| Function | Purpose | JPA standard
+
+| `sha()` | The SHA256 hash of a string. | ✖
+| `md5()` | The MD5 hash of a string. | ✖
+|===
+
+These functions accept a string and return `byte[]`.
+The return value is compatible with the byte array produced by Java's `MessageDigest`.
+
 [[embedding-sql]]
 ==== Embedding SQL expressions