README update with note that double-quoted strings now interpolate $-vars.
README update with note that double-quoted strings now interpolate $-vars.

perl6/nqp-rx,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,perl6/nqp-rx,cygx/nqp,cygx/nqp,cygx/nqp