Update license information of src/README.md

src/README.md

-Distributed under the terms of *GNU GPL-3.0-or-later*
-
 # Folder instructions
 
 This directory collects the source code of the original programs and the development folders.
@@ -37,3 +35,20 @@ In all cases, build commands executed through `make` will output the object file
    > ./np_cluster
 
 7. Check the consistency between the text files named `OCLU` and `c_OCLU`
+
+# License
+
+   Copyright 2004 INAF - Osservatorio Astronomico di Cagliari
+
+   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.
+