fix doc build

* doc/ref/api-data.texi (Bitwise Operations): Don't use @-commands in
  @math.  Fixes doc build.
* doc/ref/api-macros.texi (Syntax Rules): Fix example result.

doc/ref/api-data.texi

@@ -1688,7 +1688,7 @@ starts from 0 for the least significant bit.
 
 @deffn {Scheme Procedure} ash n count
 @deffnx {C Function} scm_ash (n, count)
-Return @math{floor(@var{n} * 2^@var{count})}.
+Return @math{floor(n * 2^count)}.
 @var{n} and @var{count} must be exact integers.
 
 With @var{n} viewed as an infinite-precision twos-complement
@@ -1707,7 +1707,7 @@ when @var{count} is negative.  This is an ``arithmetic'' shift.
 
 @deffn {Scheme Procedure} round-ash n count
 @deffnx {C Function} scm_round_ash (n, count)
-Return @math{round(@var{n} * 2^@var{count})}.
+Return @math{round(n * 2^count)}.
 @var{n} and @var{count} must be exact integers.
 
 With @var{n} viewed as an infinite-precision twos-complement

doc/ref/api-macros.texi

@@ -215,7 +215,7 @@ including ellipsizing and tail patterns.
     ((_ #((var val) ...) exp exp* ...)
      (let ((var val) ...) exp exp* ...))))
 (letv #((foo 'bar)) foo)
-@result{} foo
+@result{} bar
 @end example
 
 Literals are used to match specific datums in an expression, like the use of