Add Javadoc and @SInCE 2.0.0 to new methods.

Author: timw

http-cors/src/main/java/org/apache/pekko/http/cors/javadsl/model/HttpHeaderRange.java

@@ -24,6 +24,11 @@
 public abstract class HttpHeaderRange {
   public abstract boolean matches(String header);
 
+  /**
+   * Produces a new range that matches the headers of this range and the given range.
+   *
+   * @since 2.0.0
+   */
   public abstract HttpHeaderRange concat(HttpHeaderRange range);
 
   public static HttpHeaderRange create(String... headers) {

http-cors/src/main/scala/org/apache/pekko/http/cors/scaladsl/model/HttpHeaderRange.scala

@@ -28,6 +28,11 @@ import pekko.util.Helpers
 sealed abstract class HttpHeaderRange extends javadsl.model.HttpHeaderRange {
   override def concat(range: javadsl.model.HttpHeaderRange): HttpHeaderRange
 
+  /**
+   * Operator alias for [[concat]].
+   * 
+   * @since 2.0.0
+   */
   def ++(range: javadsl.model.HttpHeaderRange): HttpHeaderRange = concat(range)
 }