Add NOTICE file for CNCF donation

NOTICE

@@ -1,2 +1,19 @@
-Karpenter
-Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+When donating the karpenter-core project to the CNCF, not all contributors were reached
+to sign the CNCF CLA prior to donation. As such, according to the CNCF rules to donate a repository,
+we must add a NOTICE referencing section 7 of the CLA with a list of developers who could not be reached.
+
+> 7. Should You wish to submit work that is not Your original creation, You may
+> submit it to the Foundation separately from any Contribution, identifying the
+> complete details of its source and of any license or other restriction
+> (including, but not limited to, related patents, trademarks, and license
+> agreements) of which you are personally aware, and conspicuously marking the
+> work as "Submitted on behalf of a third-party: [named here]".
+
+Submitted on behalf of a third-party: @sergkondr
+Submitted on behalf of a third-party: @abeer-stripe
+Submitted on behalf of a third-party: @shikai93
+Submitted on behalf of a third-party: @gfcroft
+Submitted on behalf of a third-party: @lucass4
+Submitted on behalf of a third-party: @wkaczynski
+Submitted on behalf of a third-party: @spring1843
+Submitted on behalf of a third-party: @njtran