[ci skip] tfw you forget to add it to the table of contents

docs/source/api/api-top.rst

@@ -12,6 +12,7 @@ Browse the various function and classes :doc:`Sol<../index>` utilizes to make yo
    state
    table
    proxy
+   containers
    as_table
    usertype
    simple_usertype

docs/source/usertypes.rst

@@ -22,4 +22,5 @@ There are also some notes about guarantees you can find about usertypes, and the
 * The first ``sizeof( void* )`` bytes is always a pointer to the typed C++ memory. What comes after is based on what you've pushed into the system according to :doc:`the memory specification for usertypes<api/usertype_memory>`. This is compatible with a number of systems.
 * Member methods, properties, variables and functions taking ``self&`` arguments modify data directly
 	- Work on a copy by taking or returning a copy by value.
-* The actual metatable associated with the usertype has a long name and is defined to be opaque by the Sol implementation.
+* The actual metatable associated with the usertype has a long name and is defined to be opaque by the Sol implementation.
+* Containers get pushed as special usertypes, but can be disabled if problems arising as detailed :doc:`here<api/containers>`.