docs: update description for classHashPrefix

website/packages/docs/src/pages/pkg-babel-plugin.mdx

@@ -96,10 +96,12 @@ Extensions that we should consider code. We use these to identify if a file shou
 
 #### classHashPrefix
 
-Adds a prefix to the generated hashed css rule names.
+Adds a prefix to the generated hashed css rule names. The valued passed to it gets hashed in conjunction with the rest of the rule declaration.
 
 This is useful when `@compiled` is being used in a micro frontend environment by multiple packages and you want to avoid specificity issues.
 
+The currently accepted regex for this value is `^[a-zA-Z\-_]+[a-zA-Z\-_0-9]*$`.
+
 - Type: `string`
 - Default: `undefined`