Add decont to glossary

Author: zoffixznet

doc/Language/glossary.pod6

@@ -301,6 +301,13 @@ in the friendly Perl 6 community.
 Original author of the L<#Exegesis> (among many other things).
 See also L<https://en.wikipedia.org/wiki/Damian_Conway>.
 
+=head1 decont
+X<|decont>
+
+Short for "decontainerize", meaning to remove an item L<from its C«Scalar»
+container|https://docs.perl6.org/language/containers>, often to obtain
+L<a different behaviour|https://perl6advent.wordpress.com/2017/12/02/#theoneandonly> for items that have it.
+
 =head1 diffy
 X<|diffy>