Update reference docs to latest version of draft standard and fill in

some missing details.

[SVN r56558]

libs/unordered

@@ -1 +1 @@
-Subproject commit 63e04cfb604101e595a50fb7c1fdeab82f81bd57
+Subproject commit 55eafdf0eef5dca21519d7052b13a40ce806dac1