[over.oper] Clarify that operator= cannot be overloaded for enumerations.

Author: jensmaurer

source/overloading.tex

@@ -3443,15 +3443,12 @@
 enumeration, or a reference to an enumeration.
 It is not possible to change the precedence, grouping, or number of operands
 of operators.
-The meaning of the operators
-\tcode{=},
-(unary)
-\tcode{\&},
-and
-\tcode{,}
-(comma), predefined for each type, can be changed for specific
-class and enumeration types by
+The meaning of
+the operators \tcode{=}, (unary) \tcode{\&}, and \tcode{,} (comma),
+predefined for each type, can be changed for specific class types by
 defining operator functions that implement these operators.
+Likewise, the meaning of the operators (unary) \tcode{\&} and \tcode{,} (comma)
+can be changed for specific enumeration types.
 \indextext{overloaded operator!inheritance of}%
 Operator functions are inherited in the same manner as other base class
 functions.