Fix tabs in --help

[martin-ncs]

The current --help is having some problems to render properly:

  <remote>s are remote connections tunneled through the server, each of
  which come in the form:
   	local-port:local-host->remote-port:remote-host

	■ local-port (port on server) is required*.
    ■ local-host (interface on server) defaults to 0.0.0.0 (all interfaces).
	■ remote-port is required*.
    ■ remote-host defaults to 127.0.0.1

	example remotes
      8080->80
      8080:0.0.0.0->80
      8089->80:neverssl.com

This was caused by having mixed tabs/spaces in the help texts.

[mahdi-torabi]

Thanks. Looks good to me.