Poor description of mechanism-name attribute

Description in model : "The name of the mechanism the configuration applies to"

XSD description is better and explains why is mechanism-name optional: "This configuration will only apply where a mechanism with the name specified is used. If this attribute is omited then this will match any mechanism name."

Synchronize descriptions - use description from XSD. in model
Issue applies to attribute occurences in

• http-server-mechanism-factory
• sasl-authentication-factory

Also applies to description in operation add description. Not sure if this is automatic, therefore mentioning it explicitly.

/subsystem=elytron/http-authentication-factory=a:read-operation-description(name=add)