* scheme-control.texi (Multiple Values): Documented concept of

	* scheme-control.texi (Multiple Values): Documented concept of
	multiple values, added docs for `receive'.
	(begin): Documented `begin'.
	(if cond case): Documented `if', `cond' and `case'.
	(and or): Documented `and' and `or'.
	(while do): Documented `do' and `while'.

	* scheme-procedures.texi (Optional Arguments): Split the node,
	added introductory text, added menu for subsections.
	(let-optional Reference, let-keywords Reference),
	(lambda* Reference, define* Reference): Added syntax documentation
	for all exported procedures from (ice-9 optargs).