[expr.pre,conv.general] Add spaces around operators (#7903)

Author: Andreas-Krug

source/expressions.tex

@@ -39,7 +39,7 @@
 obey the rules for syntax and evaluation order specified in \ref{expr.compound},
 but the requirements of operand type and value category are replaced
 by the rules for function call. Relations between operators, such as
-\tcode{++a} meaning \tcode{a+=1}, are not guaranteed for overloaded
+\tcode{++a} meaning \tcode{a += 1}, are not guaranteed for overloaded
 operators\iref{over.oper}.
 \end{note}
 
@@ -556,7 +556,7 @@
 \pnum
 An expression $E$ can be
 \defnx{implicitly converted}{conversion!implicit} to a type \tcode{T} if and only if the
-declaration \tcode{T t=$E$;} is well-formed, for some invented temporary
+declaration \tcode{T t = $E$;} is well-formed, for some invented temporary
 variable \tcode{t}\iref{dcl.init}.
 
 \pnum