fix typo

docs/release_guide.pod

@@ -125,7 +125,7 @@ the number of available tests, look at "docs/spectest-progress.csv".
 If it hasn't been updated recently, use "git log docs/spectest-progress.csv"
 to find out who has been updating it and seek out this person for an
 update. You can also run F<tools/test_summary.pl> to obtain the latest data.
-To get the total number of available spectes, the tool C<ack> (see
+To get the total number of available spectests, the tool C<ack> (see
 L<http://search.cpan.org/dist/ack/>) has to be installed and be found in
 C<$PATH>.