[expr.sub,expr.pre.incr] Add spaces around operators

Author: Andreas-Krug

source/expressions.tex

@@ -3512,7 +3512,7 @@
 \tcode{\&x[0]}.
 \end{footnote}
 The expression \tcode{E1[E2]} is identical (by definition) to
-\tcode{*((E1)+(E2))},
+\tcode{*((E1) + (E2))},
 except that in the case of an array operand, the result is an lvalue
 if that operand is an lvalue and an xvalue otherwise.
 
@@ -5134,8 +5134,8 @@
 shall not be of type \cv{}~\tcode{bool}.
 An operand with volatile-qualified type is deprecated;
 see~\ref{depr.volatile.type}.
-The expression \tcode{++x} is otherwise equivalent to \tcode{x+=1} and
-the expression \tcode{--x} is otherwise equivalent to \tcode{x-=1}\iref{expr.assign}.
+The expression \tcode{++x} is otherwise equivalent to \tcode{x += 1} and
+the expression \tcode{--x} is otherwise equivalent to \tcode{x -= 1}\iref{expr.assign}.
 \begin{note}
 For postfix increment and decrement, see~\ref{expr.post.incr}.
 \end{note}