docs: updare CONTRIBUTING with copyright guidlines

CONTRIBUTING.md

@@ -104,12 +104,30 @@ oneDAL uses `Doxygen` for inline comments in public header files that are used t
 oneDAL is licensed under [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0). By contributing to the project, you agree to the license and copyright terms therein and release your contribution under these terms.
 
 ### Copyright Guidelines for Contributions
-1. Each new file added to the project must include the following copyright notice:
-    ```plaintext
-    Copyright contributors to the oneDAL project
-    ```
-2. When modifying an existing file with an Intel Corporation copyright notice, do not remove the original notice. Simply add your own copyright notice with the following line:
-    ```plaintext
-    Copyright <YYYY> Intel Corporation
-    Copyright contributors to the oneDAL project
-    ```
+Each new file added to the project must include the following copyright notice:
+```
+Copyright contributors to the oneDAL project
+```
+Here is what a copyright header for C/C++ code would look like:
+```
+/*
+ * Copyright contributors to the oneDAL project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+```
+When modifying an existing file with an Intel Corporation copyright notice, do not remove the original notice. Simply add your own copyright notice with the following line:
+```
+Copyright <YYYY> Intel Corporation
+Copyright contributors to the oneDAL project
+```