feat(redis): added --db flag to pick redis DB to connect to

scripts/rcstack/rcstack

@@ -1186,6 +1186,12 b' rcstack_cli_redis_usage() {'
     printf "    Default: $PWD/.custom/.runtime.env\n"
     echo
 
+    # :flag.usage
+    printf "  %s\n" "--db DB"
+    printf "    select Redis db, defaults 0\n"
+    printf "    Default: 0\n"
+    echo
+
     # :command.usage_fixed_flags
     printf "  %s\n" "--help, -h"
     printf "    Show this help\n"