README: Document new --chroot-dir and --setuid options

README

@@ -181,6 +181,7 @@ Options for both config file and command line:
 --api-port          Port number of miner API (default: 4028)
 --balance           Change multipool strategy from failover to even share balance
 --benchmark         Run BFGMiner in benchmark mode - produces no shares
+--chroot-dir <arg>  Chroot to a directory right after startup
 --cmd-idle <arg>    Execute a command when a device is allowed to be idle (rest or wait)
 --cmd-sick <arg>    Execute a command when a device is declared sick
 --cmd-dead <arg>    Execute a command when a device is declared dead
@@ -228,6 +229,7 @@ Options for both config file and command line:
 --sched-start <arg> Set a time of day in HH:MM to start mining (a once off without a stop time)
 --sched-stop <arg>  Set a time of day in HH:MM to stop mining (will quit without a start time)
 --scrypt            Use the scrypt algorithm for mining (non-bitcoin)
+--setuid <arg>      Username of an unprivileged user to run as
 --sharelog <arg>    Append share log to file
 --shares <arg>      Quit after mining N shares (default: unlimited)
 --show-processors   Show per processor statistics in summary