Markup fixes for doc/lispref

* doc/lispref/control.texi (Pattern matching case statement):
* doc/lispref/positions.texi (List Motion):
* doc/lispref/streams.texi (Output Functions):
* doc/lispref/strings.texi (Text Comparison):
* doc/lispref/text.texi (Document Object Model):
Markup fixes.
* doc/lispref/sequences.texi (Sequence Functions): Copyedits.
* doc/lispref/windows.texi (Windows): Sync @menu order with @node order.