Java 14: add PREVIEW FEATURE notes to QLDoc

Author: yo-h

java/ql/src/semmle/code/java/Expr.qll

@@ -1136,10 +1136,18 @@ class InstanceOfExpr extends Expr, @instanceofexpr {
     else result.isNthChildOf(this, 0)
   }
 
-  /** Holds if this `instanceof` expression uses pattern matching. */
+  /**
+   * PREVIEW FEATURE in Java 14. Subject to removal in a future release.
+   *
+   * Holds if this `instanceof` expression uses pattern matching.
+   */
   predicate isPattern() { exists(getLocalVariableDeclExpr()) }
 
-  /** Gets the local variable declaration of this `instanceof` expression if pattern matching is used. */
+  /**
+   * PREVIEW FEATURE in Java 14. Subject to removal in a future release.
+   *
+   * Gets the local variable declaration of this `instanceof` expression if pattern matching is used.
+   */
   LocalVariableDeclExpr getLocalVariableDeclExpr() { result.isNthChildOf(this, 0) }
 
   /** Gets the access to the type on the right-hand side of the `instanceof` operator. */

java/ql/src/semmle/code/java/Type.qll

@@ -615,7 +615,11 @@ class Class extends RefType, @class {
   }
 }
 
-/** A record declaration. */
+/**
+ * PREVIEW FEATURE in Java 14. Subject to removal in a future release.
+ *
+ * A record declaration.
+ */
 class Record extends Class {
   Record() { isRecord(this) }
 }