RT2609: Typo in EXAMPLE section of req.pod

The x509_extensions should be req_extensions in the
config example in req.pod

Reviewed-by: tjh@cryptsoft.com

doc/apps/req.pod

@@ -535,7 +535,7 @@ Sample configuration file prompting for field values:
  default_keyfile 	= privkey.pem
  distinguished_name	= req_distinguished_name
  attributes		= req_attributes
- x509_extensions	= v3_ca
+ req_extensions		= v3_ca
 
  dirstring_type = nobmp