docs: add CONTRIBUTORS.md file

Signed-off-by: Adam Tagscherer <adam.tagscherer@gmail.com>

Author: adamtagscherer

CONTRIBUTORS.md

@@ -0,0 +1,10 @@
+# Contributors to SLIM
+
+CONTRIBUTOR file should only contain list of copyright holder (i.e. employers of
+maintainers). All files that support comments should include standard header for
+the project. AGNTCY uses the following file header:
+
+Copyright AGNTCY Contributors (https://github.com/agntcy)
+SPDX-License-Identifier: Apache-2.0
+
+1. Cisco Systems Inc.