OKO-81 📄 [LICENSE] Add GNU AGLP file and corresponding license...

MR writing steps

• I have set the MR title
• I have written the MR description
• I have ensured the MR pipeline has passed
• I added a reviewer to the MR so they can review my code
• I have treated the MR comments
• I have ensured the release notes have been updated according to the new changes
• I have ensured the MR pipeline passes after the new changes

Goal & Changes

What? Why?

Add GNU AGLP file and corresponding license notice on sources file