[vector.cons] Fix subclause heading.

Remove mention of "assignment", which is not specified here.

Author: jensmaurer

source/containers.tex

@@ -5702,7 +5702,7 @@
 \tcode{T} shall be complete before any member of the resulting specialization
 of \tcode{vector} is referenced.
 
-\rSec3[vector.cons]{Constructors, copy, and assignment}
+\rSec3[vector.cons]{Constructors}
 
 \indexlibraryctor{vector}
 \begin{itemdecl}