perldelta entry for the varname improvement

Author: book

pod/perldelta.pod

@@ -242,7 +242,12 @@ XXX Changes (i.e. rewording) of diagnostic messages go here
 
 =item *
 
-XXX Describe change here
+The names of variables whose names begin with a caret and are longer
+than two characters are now wrapped in braces, like they have to be in
+the source code.
+
+For example, C<Use of uninitialized value $^FOO> will be now
+be correctly shown as C<Use of uninitialized value ${^FOO}>.
 
 =back