[R6RS] editorial policy regarding duplicate text

[dyb at cs.indiana.edu]

The descriptions of syntax-rules (in the base) and syntax-case (in its
own chapter) contain a lot of duplicated text, in particular the text
describing patterns, templates, and the process of matching patterns
and producing output.  Would it be better for the syntax-case chapter
to refer back to the syntax-rules section of the base chapter?

Kent