perlapi: How to find when API item added to Perl

This adds text to this pod that shows how to use ppport to find when an
API element came into being in perl

Author: khwilliamson

autodoc.pl

@@ -2780,6 +2780,20 @@ ($destpod)
 |to be documented.  Patches welcome!  The interfaces of these are subject to
 |change without notice.
 |
+|To find out what release an element came into being, use
+|
+| perl dist/ppport.h --api-info=element
+|
+|You may also use a pattern
+|
+| perl dist/ppport.h --api-info=/./
+|
+|displays all possible public api elements, but not items in L<perlintern>.
+|Some elements have been backported in L<Devel::PPPort> so that they are
+|usable in earlier versions than they otherwise would be available.  The
+|display also includes information as to what the earliest possible version
+|such an element may be used in; as well as some hints and cautions.
+|
 |Some of the functions documented here are consolidated so that a single entry
 |serves for multiple functions which all do basically the same thing, but have
 |some slight differences.  For example, one form might process magic, while

pod/perldelta.pod

@@ -219,7 +219,8 @@ Additionally, the following selected changes have been made:
 
 =item *
 
-XXX Description of the change here
+L<perlapi> now contains information about how to find what release of
+Perl first contained an API element 
 
 =back