[class.mem.general] Clarify class completeness

Author: jensmaurer

source/classes.tex

@@ -605,11 +605,10 @@
 \end{note}
 
 \pnum
-A class is regarded as complete
-where its definition is reachable and
-within its complete-class contexts;
-otherwise it is regarded as incomplete within its own class
-\grammarterm{member-specification}.
+A class \tcode{C} is complete at a program point $P$
+if the definition of \tcode{C} is reachable from $P$\iref{module.reach}
+or if $P$ is in a complete-class context of \tcode{C}.
+Otherwise, \tcode{C} is incomplete at $P$.
 
 \pnum
 In a \grammarterm{member-declarator},