perldelta - Fix spelling of modernize, as per cb60726

(-ize also happens to be the more widely used UK spelling, in addition to
being the US spelling; -ise is a (UK-specific) variant spelling)

Author: steve-m-hay

pod/perldelta.pod

@@ -81,7 +81,7 @@ Additionally, the following selected changes have been made:
 =item *
 
 The reference manual for writing Perl XS code has been completely rewritten and
-modernised.  It is about twice the size of the old file, and promotes more
+modernized.  It is about twice the size of the old file, and promotes more
 modern XS syntax, such as ANSI signatures.
 
 =back