Describe details about "resteasy.original.webapplicationexception.behavior" property with respect to base EAP and EAP XP to RN and web-services guide.

Originally, MP Config was in EAP as technology preview. But MP Config was removed from EAP, and added to EAP XP.

Consequence of this: users can set "resteasy.original.webapplicationexception.behavior" property as servlet property or system property in EAP XP. But users can set this property as servlet property only if EAP XP is not installed (user have base EAP only).

Servlet property can be set in web.xml:

    <context-param>
        <param-name>resteasy.original.webapplicationexception.behavior</param-name>
        <param-value>true</param-value>
    </context-param>

• Related EAP7 jira: EAP7-1569
• See also GSS request with additional explanation (cc bmaxwell)
• See also this suggestion:

  And perhaps put a note in the docs where we mention these tech preview MP Config is now just in EAP XP would be good.