* doc/ref/r6rs.texi: Fix erroneous usage of @pxref; add pointers from
`(rnrs conditions)' and `(rnrs arithmetic bitwise)' to SRFI-35 and
SRFI-60 sections; remove reference to `fold'.
* module/ice-9/psyntax.scm (set!): Handle variable transformers; though,
they cannot produce definitions.
(make-variable-transformer): New procedure.
(identifier-syntax): Allow the R6RS form that makes variable
transformers.
* module/ice-9/psyntax-pp.scm: Regenerated.
* doc/ref/r6rs.texi (R6RS Incompatibilities): Remove letrec* item, and
add set! restriction.
* doc/ref/r6rs.texi (R6RS Support): Skeleton of docs on our R6RS
support.
* doc/ref/guile.texi:
* doc/ref/Makefile.am: Add r6rs.texi.
* doc/ref/intro.texi: Add a link to r6rs.texi.