Fix typos in x509.pod

CLA: trivial
Reviewed-by: NTomas Mraz <tomas@openssl.org>
Reviewed-by: NPaul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/14783)

doc/man7/x509.pod

@@ -11,7 +11,7 @@ x509 - X.509 certificate handling
 =head1 DESCRIPTION
 
 An X.509 certificate is a structured grouping of information about
-an individual, a device, or anything one can imagine.  A X.509 CRL
+an individual, a device, or anything one can imagine.  An X.509 CRL
 (certificate revocation list) is a tool to help determine if a
 certificate is still valid.  The exact definition of those can be
 found in the X.509 document from ITU-T, or in RFC3280 from PKIX.
@@ -24,7 +24,7 @@ X509_REQ is used to express such a certificate request.
 
 To handle some complex parts of a certificate, there are the types
 X509_NAME (to express a certificate name), X509_ATTRIBUTE (to express
-a certificate attributes), X509_EXTENSION (to express a certificate
+a certificate attribute), X509_EXTENSION (to express a certificate
 extension) and a few more.
 
 Finally, there's the supertype X509_INFO, which can contain a CRL, a