Update help.red

Added hint for quit in the help function.

result:
-=== Red Console alpha version ===-
Type HELP for starting information.

red>> help
Use HELP or ? to see built-in info:

    help insert
    ? insert

To see all words of a specific datatype:

    ? native!
    ? function!
    ? datatype!

Other useful functions:

    ?? - display a variable and its value
    probe - print a value (molded)
    source func - show source code of func
    what - show a list of known functions
    system/version - display version number and build date
    q or quit - leave the Red console

red>>