Fixed a typo in a man page

Reviewed-by: NAndy Polyakov <appro@openssl.org>
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5508)

doc/man1/openssl.pod

@@ -208,7 +208,7 @@ Generate pseudo-random bytes.
 
 =item L<B<rehash>|rehash(1)>
 
-Create symbolic links to certficate and CRL files named by the hash values.
+Create symbolic links to certificate and CRL files named by the hash values.
 
 =item L<B<req>|req(1)>