[unord.set.overview] Add line breaks in excessively long line

Author: jwakely

source/containers.tex

@@ -12336,7 +12336,13 @@
 of a container\iref{container.reqmts},
 of an allocator-aware container\iref{container.alloc.reqmts},
 of an unordered associative container\iref{unord.req}.
-It provides the operations described in the preceding requirements table for unique keys; that is, an \tcode{unordered_set} supports the \tcode{a_uniq} operations in that table, not the \tcode{a_eq} operations. For an \tcode{unordered_set<Key>} the \tcode{key_type} and the \tcode{value_type} are both \tcode{Key}. The \tcode{iterator} and \tcode{const_iterator} types are both constant iterator types. It is unspecified whether they are the same type.
+It provides the operations described in the preceding requirements table for unique keys;
+that is, an \tcode{unordered_set} supports the \tcode{a_uniq} operations in that table,
+not the \tcode{a_eq} operations.
+For an \tcode{unordered_set<Key>} the \tcode{key_type}
+and the \tcode{value_type} are both \tcode{Key}.
+The \tcode{iterator} and \tcode{const_iterator} types are both constant iterator types.
+It is unspecified whether they are the same type.
 
 \pnum
 Subclause~\ref{unord.set} only describes operations on \tcode{unordered_set} that