[class.base.init] Use \defnadj to introduce delegating and target constructor (#6252)

Author: languagelawyer

source/classes.tex

@@ -5461,8 +5461,8 @@
 \grammarterm{class-or-decltype} that denotes the constructor's class itself. If a
 \grammarterm{mem-initializer-id} designates the constructor's class,
 it shall be the only \grammarterm{mem-initializer}; the constructor
-is a \term{delegating constructor}, and the constructor selected by the
-\grammarterm{mem-initializer} is the \term{target constructor}.
+is a \defnadj{delegating}{constructor}, and the constructor selected by the
+\grammarterm{mem-initializer} is the \defnadj{target}{constructor}.
 The target constructor is selected by overload resolution.
 Once the target constructor returns, the body of the delegating constructor
 is executed. If a constructor delegates to itself directly or indirectly,