Fix grammar error in verify pod. PR#3355

doc/apps/verify.pod

@@ -386,7 +386,7 @@ an application specific error. Unused.
 
 =head1 BUGS
 
-Although the issuer checks are a considerably improvement over the old technique they still
+Although the issuer checks are a considerable improvement over the old technique they still
 suffer from limitations in the underlying X509_LOOKUP API. One consequence of this is that
 trusted certificates with matching subject name must either appear in a file (as specified by the
 B<-CAfile> option) or a directory (as specified by B<-CApath>. If they occur in both then only