[indirect.asgn] Change "contained value" to "owned object" (#7822)

Author: xmcgcg

source/memory.tex

@@ -6282,7 +6282,7 @@
 If an exception is thrown during
 the call to \tcode{T}{'s} selected copy constructor, no effect.
 If an exception is thrown during the call to \tcode{T}{'s} copy assignment,
-the state of its contained value
+the state of its owned object
 is as defined by the exception safety guarantee of
 \tcode{T}{'s} copy assignment.
 \end{itemdescr}