Update license_header_template.

Add SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause

Signed-off-by: Achim Kraus <achim.kraus@cloudcoap.net>

license_header_template.txt

@@ -1,17 +1,16 @@
-/*******************************************************************************
- * Copyright (c) <year (e.g. 2020)> <(company) name> and others.
+/********************************************************************************
+ * Copyright (c) {date} Contributors to the Eclipse Foundation
  * 
- * All rights reserved. This program and the accompanying materials
- * are made available under the terms of the Eclipse Public License v2.0
- * and Eclipse Distribution License v1.0 which accompany this distribution.
+ * See the NOTICE file(s) distributed with this work for additional
+ * information regarding copyright ownership.
  * 
- * The Eclipse Public License is available at
- *    http://www.eclipse.org/legal/epl-v20.html
- * and the Eclipse Distribution License is available at
- *    http://www.eclipse.org/org/documents/edl-v10.html.
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * https://www.eclipse.org/legal/epl-2.0, or the Eclipse Distribution License
+ * v1.0 which is available at
+ * https://www.eclipse.org/org/documents/edl-v10.php.
  * 
- * Contributors:
- *    <(company) name> - initial creation
- ******************************************************************************/
+ * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
+ ********************************************************************************/
 
-Please replace all <symbolic name> tags with the information proper for you!
+Please replace {date} with the year of the contribution!