Reorganinze and add to installs dir

installs_and_builds/s31_docker

@@ -0,0 +1,21 @@
+#!/bin/zsh
+
+setup_docker_on_debian() {
+    # refer to https://docs.docker.com/engine/install/debian/
+    # build this function based on that
+    # in that, could use BOX_SETUP_INSTALL_COMMAND or just apt install
+    echo "setup_docker_on_debian function not implemented"
+}
+
+# TODO: decide on docker vs others; below is included just for reference
+# case $BOX_SETUP_OS in
+#     (arch | artix)
+#         ${=BOX_SETUP_INSTALL_COMMAND} docker
+#         ;;
+#     (debian)
+#         setup_docker_on_debian
+#         ;;
+#     (macos)
+#         ${=BOX_SETUP_INSTALL_COMMAND} docker
+#         ;;
+# esac