fix(license): add copyleft file

JulienChampagnol · JulienChampagnol · commit 670ad6d835c2 · 2023-09-20T14:15:04.000+02:00
diff --git a/COPYLEFT b/COPYLEFT
@@ -0,0 +1,4 @@
+## Dependencies
+
+Nginx: BSD-2-Clause
+Copyright (C) 2011-2023 Nginx, Inc.
