Make the regular expression element naming and cardinality consistent about epp-registry-mapping HOT 2 CLOSED

For the naming, I believe that the pattern should be [attr]Regex, where [attr] is a reference to the attribute that the regular expression applies to. For the cardinality, a PCRE can effectively define the expected syntax for the attributes in the Registry Mapping in a single expression, so it is best for the regular expression to be handled via a single element.

from epp-registry-mapping.

Updated to make the regular expression elements follow a consistent naming convention and cardinality. Changed registry:regex to registry:nameRegex under the registry:domainName element, and changed to a single element. Changed the registry:nameRegex under the registry:host element to a single element.

from epp-registry-mapping.