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

Author: jwakely

source/containers.tex

@@ -11271,7 +11271,12 @@
 of a container\iref{container.reqmts},
 of an allocator-aware container\iref{container.alloc.reqmts}, and
 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_map} supports the \tcode{a_uniq} operations in that table, not the \tcode{a_eq} operations. For an \tcode{unordered_map<Key, T>} the \tcode{key_type} is \tcode{Key}, the \tcode{mapped_type} is \tcode{T}, and the \tcode{value_type} is \tcode{pair<const Key, T>}.
+It provides the operations described in the preceding requirements table for unique keys;
+that is, an \tcode{unordered_map} supports the \tcode{a_uniq} operations in that table,
+not the \tcode{a_eq} operations.
+For an \tcode{unordered_map<Key, T>} the \tcode{key_type} is \tcode{Key},
+the \tcode{mapped_type} is \tcode{T},
+and the \tcode{value_type} is \tcode{pair<const Key, T>}.
 
 \pnum
 Subclause~\ref{unord.map} only describes operations on \tcode{unordered_map} that