chore: adding NOTICE file (#901)

Signed-off-by: Dario Tranchitella <[email protected]>

Author: prometherion

NOTICE

@@ -0,0 +1,15 @@
+Kamaji — The Kubernetes Control Plane Manager: copyright 2022 Clastix Labs
+Licensed under the Apache License, Version 2.0: https://kamaji.clastix.io
+
+This product includes software developed by Clastix Labs and the Kamaji open-source community under the Apache License, Version 2.0.
+
+Kamaji powers Kubernetes Control Planes at scale for companies worldwide.
+
+We encourage all commercial products and services using Kamaji to acknowledge this publicly and join our growing ecosystem of adopters.
+
+You can support the Kamaji community by:
+- Listing Kamaji in your product's "Open Source Credits" or similar section
+- Adding your organization to the Adopters list on GitHub: https://github.com/clastix/kamaji/blob/master/ADOPTERS.md
+- Mentioning Kamaji on your company or product website
+
+Public acknowledgement strengthens the open-source ecosystem and helps ensure the sustainability of the project you rely on.