readme: Update v8 help output
readme: Update v8 help output

Update output of v8 help in README.md to match the current output and list all the available commands and options.
hhellyer/llnode,hhellyer/llnode,rnchamberlain/llnode,rnchamberlain/llnode,hhellyer/llnode,rnchamberlain/llnode,hhellyer/llnode,rnchamberlain/llnode