docs: correct code comment — rule diverges from jsx-a11y on role-fallback semantics

The previous comment said this matched jsx-a11y, but jsx-a11y validates
every recognised role token while we check only the first recognised
role per ARIA role-fallback semantics. Update the comment to reflect
the PR description's stated behavior.

Author: johanrd

lib/rules/template-require-mandatory-role-attributes.js

@@ -40,7 +40,9 @@ function splitRoleTokens(value) {
 }
 
 // For an ARIA role-fallback list like "combobox listbox", check required
-// attributes against the FIRST recognised role (the primary) — matches jsx-a11y.
+// attributes against the FIRST recognised role (the primary) per ARIA 1.2
+// role-fallback semantics — a user agent picks the first role it recognises.
+// Diverges from jsx-a11y, which validates every recognised token.
 function getMissingRequiredAttributes(roleTokens, foundAriaAttributes) {
   for (const role of roleTokens) {
     const roleDefinition = roles.get(role);