tokenize/README.md: Fix the comment on --
tokenize/README.md: Fix the comment on --

"--" is now handled by MPUNC.
IN the sample corpora there are also enough constructs that need tokenization.

linas/link-grammar,ampli/link-grammar,opencog/link-grammar,linas/link-grammar,ampli/link-grammar,linas/link-grammar,opencog/link-grammar,linas/link-grammar,ampli/link-grammar,linas/link-grammar,opencog/link-grammar,ampli/link-grammar,opencog/link-grammar,ampli/link-grammar,linas/link-grammar,opencog/link-grammar,opencog/link-grammar,ampli/link-grammar,ampli/link-grammar,linas/link-grammar,linas/link-grammar,linas/link-grammar,opencog/link-grammar,ampli/link-grammar,opencog/link-grammar,opencog/link-grammar,ampli/link-grammar