Update setup.sh

bin/setup.sh

@@ -1,5 +1,6 @@
 #!/usr/bin/env sh
 # ArchiveBox Setup Script: https://github.com/ArchiveBox/ArchiveBox
+# Supported Platforms: Ubuntu/Debian/FreeBSD/macOS
 # Usage:
 #    curl 'https://raw.githubusercontent.com/ArchiveBox/ArchiveBox/dev/bin/setup.sh' | sh