[container.adaptors.general] Also mention flat_multi{map,set} adaptors.

Also group the names-per-header by joining them with "and", to make
the use of "respectively" less confusing.

Author: tkoeppe

source/containers.tex

@@ -12974,8 +12974,17 @@
 \rSec2[container.adaptors.general]{In general}
 
 \pnum
-The headers \libheader{queue}, \libheader{stack}, \libheader{flat_map}, and \libheader{flat_set} define the container adaptors
-\tcode{queue}, \tcode{priori\-ty_queue}, \tcode{stack}, \tcode{flat_map}, and \tcode{flat_set}, respectively.
+The headers
+\libheader{queue},
+\libheader{stack},
+\libheader{flat_map},
+and \libheader{flat_set}
+define the container adaptors
+\tcode{queue} and \tcode{priority_queue},
+\tcode{stack},
+\tcode{flat_map} and \tcode{flat_multimap},
+and \tcode{flat_set} and \tcode{flat_multiset},
+respectively.
 
 \pnum
 Each container adaptor takes