Update doc on RAKU_EXCEPTIONS_HANDLER

Author: lizmat

doc/Programs/03-environment-variables.pod6

@@ -30,16 +30,17 @@ error.
 
 =head2 Error message verbosity and strictness
 
+X<|RAKU_EXCEPTIONS_HANDLER>
 X<|PERL6_EXCEPTIONS_HANDLER>
-=item C<PERL6_EXCEPTIONS_HANDLER>
+=item C<RAKU_EXCEPTIONS_HANDLER>
 
 If present, the C<print_exception> routine
 will use a class of that name to process the exception for output. Rakudo
 currently ships with C<Exceptions::JSON> (invoked by setting this variable to
 C<JSON>), to override the default output. B<NOTE:> this env var was added in
-version 6.d. Early implementation has been available in Rakudo compiler as of
-version 2018.08, and before that it was available as
-C<RAKUDO_EXCEPTIONS_HANDLER>.
+version 6.e.  Early implementation has been available in Rakudo compiler
+as of version 2019.12, and before that it was available as
+C<PERL6_EXCEPTIONS_HANDLER>.
 
 X<|RAKUDO_NO_DEPRECATIONS>
 =item C<RAKUDO_NO_DEPRECATIONS>